Cross-linked fatty acid-based biomaterials

ABSTRACT

Fatty acid-based, pre-cure-derived biomaterials, methods of making the biomaterials, and methods of using them as drug delivery carriers are described. The fatty acid-derived biomaterials can be utilized alone or in combination with a medical device for the release and local delivery of one or more therapeutic agents. Methods of forming and tailoring the properties of said biomaterials and methods of using said biomaterials for treating injury in a mammal are also provided.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/104,575, filed Oct. 10, 2008. This application also claims priorityto U.S. Provisional Application No. 61/104,568, filed Oct. 10, 2008.This application is also a continuation-in-part of U.S. patentapplication Ser. No. 11/582,135, filed Oct. 16, 2006, which claimspriority to U.S. Provisional Patent Application Ser. No. 60/727,312,filed on Oct. 15, 2005. This application is also a continuation-in-partof U.S. patent application Ser. No. 11/237,264, filed Sep. 28, 2005,which claims priority to U.S. Provisional Application No. 60/613,808,filed Sep. 28, 2004. This application is also a continuation-in-part ofU.S. patent application Ser. No. 11/236,908, filed Sep. 28, 2005, whichclaims priority to U.S. Provisional Application No. 60/613,745, filedSep. 28, 2004. The entire contents of these previously filedapplications are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Vascular interventions, such as vascular reperfusion procedures, balloonangioplasty, and mechanical stent deployment, can often result invascular injury following mechanical dilation and luminal expansion of anarrowed vessel. Often, subsequent to such intravascular procedures,neointimal proliferation and vascular injury remodeling occurs along theluminal surface of the injured blood vessel; more specifically,remodeling occurs in the heart, as well as in vulnerable peripheralblood vessels like the carotid artery, iliac artery, femoral andpopliteal arteries. No known mechanical suppression means has been foundto prevent or suppress such cellular proliferation from occurringimmediately following vascular injury from mechanical reperfusionprocedures. Left untreated, restenosis commonly occurs following avascular intervention within the treated vessel lumen within weeks of avascular injury. Restenosis, induced by localized mechanical injury,causes proliferation of remodeled vascular lumen tissue, resulting inre-narrowing of the vessel lumen, which can lead to thrombotic closurefrom turbulent blood flow fibrin activation, platelet deposition andaccelerated vascular flow surface injury. Restenosis pre-disposes thepatient to a thrombotic occlusion and the stoppage of flow to otherlocations, resulting in critical ischemic events, often with morbidity.

Restenosis initiated by mechanical induced vascular injury cellularremodeling can be a gradual process. Multiple processes, includingfibrin activation, thrombin polymerization and platelet deposition,luminal thrombosis, inflammation, calcineurin activation, growth factorand cytokine release, cell proliferation, cell migration andextracellular matrix synthesis each contribute to the restenoticprocess. While the exact sequence of bio-mechanical mechanisms ofrestenosis is not completely understood, several suspected biochemicalpathways involved in cell inflammation, growth factor stimulation andfibrin and platelet deposition have been postulated. Cell derived growthfactors such as platelet derived growth factor, fibroblast growthfactor, epidermal growth factor, thrombin, etc., released fromplatelets, invading macrophages and/or leukocytes, or directly from thesmooth muscle cells, provoke proliferative and migratory responses inmedial smooth muscle cells. These cells undergo a change from thecontractile phenotype to a synthetic phenotype. Proliferation/migrationusually begins within one to two days post-injury and peaks several daysthereafter. In the normal arterial wall, smooth muscle cells proliferateat a low rate, approximately less than 0.1 percent per day.

However, daughter cells migrate to the intimal layer of arterial smoothmuscle and continue to proliferate and secrete significant amounts ofextracellular matrix proteins. Proliferation, migration andextracellular matrix synthesis continue until the damaged endotheliallayer is repaired, at which time proliferation slows within the intima,usually within seven to fourteen days post-injury. The newly formedtissue is called neointima. The further vascular narrowing that occursover the next three to six months is due primarily to negative orconstrictive remodeling.

Simultaneous with local proliferation and migration, inflammatory cellsderived from the medial layer of the vessel wall continually invade andproliferate at the site of vascular injury as part of the healingprocess. Within three to seven days post-injury, substantialinflammatory cell formation and migration have begun to accumulate alongthe vessel wall to obscure and heal over the site of the vascularinjury. In animal models, employing either balloon injury or stentimplantation, inflammatory cells may persist at the site of vascularinjury for at least thirty days. Inflammatory cells may contribute toboth the acute and protracted chronic phases of restenosis andthrombosis.

Today, a preferred approach to the local delivery of a drug to the siteof vascular injury caused by an intravascular medical device, such as acoronary stent, is to place a drug eluting coating on the device.Clinically, medical devices coated with a drug eluting coating comprisedof either a permanent polymer or degradable polymer and an appropriatetherapeutic agent have shown angiographic evidence that vascular wallproliferation following vascular injury and/or vascular reperfusionprocedures can be reduced, if not eliminated, for a certain period oftime subsequent to balloon angioplasty and/or mechanical stentdeployment. Local delivery of a single sirolimus or taxol compound via adrug eluting medical device has been shown to be effective at minimizingor preventing cellular proliferation and cellular remodeling whenapplied immediately after vascular injury. Various analogs of these twoanti-proliferative compound examples have also been shown experimentallyand clinically to exhibit similar anti-proliferative activity withsimilar drug eluting coatings. However, anti-proliferative compoundssuch as sirolimus and taxol, together with a polymeric drug elutingcoating have also been shown clinically to exhibit a number of toxicside effects, during and after principal drug release from the drugeluting coating. These chronic and or protracted side effects placelimits on the amount of drug that can actually be delivered over a givenperiod of time, as well as challenge the compatibility of the polymercoatings used to deliver a therapeutic agent locally to the site of thevascular injury when applied directly to a site of inflammation and orcellular remodeling. In addition, local overdosage of compounds likesirolimus and taxol can prevent, limit or even stop cellular remodelingor proliferation in and around the localized tissue area of the medicaldevice. For example, a lack of endothelial cell coverage during theinterruption of cell proliferation throughout the vascular injuryhealing process exhibits a high potential for luminal thrombosis wherebyfibrin and a constant deposition of platelets blanket the exposed andnon-healed medical device and/or damaged vascular wall. Withoutuninterrupted systemic support or administration of an anti-plateletmedication like clopidegrel combined with an anti-clotting agent, suchas ASA, prior to and following deployment of a drug eluting medicaldevice, such devices have been shown clinically to thrombose and occludewithin days of deployment. In addition, although these commerciallyavailable drug eluting polymer coatings employed on medical devices aregenerally characterized as being biocompatible, the lack of chemicalhydrolysis, degradation and absorption of these polymer-basedchemistries into smaller, easier to metabolize chemical components orproducts have now been clinically demonstrated to initiate a protractedlocalized inflammatory response at the site of the vascular injury,which may lead to unexpected thrombotic occlusion within days ofstopping anti-platelet medication.

Wound healing or response to in-vivo injury (e.g., hernia repair)follows the same general biological cascade as in vascular injury (see,e.g., Y. C. Cheong et al. Human Reproduction Update. 2001; Vol. 7, No.6, pgs 556-566). This cascade includes inflammation of native tissuefollowed by migration and proliferation of cells to mitigate theinflammatory response, including platelets and macrophages, and asubsequent healing phase which includes fibrin deposition and theformation of fibrin matrix followed by tissue remodeling. In the case ofhernia repair, abnormal peritoneal healing can occur when there is theexpression of inflammatory cytokines from macrophages (e.g., α-TNF) thatcan result in an inability of the fibrin matrix to be properly brokendown and can result in the formation of adhesions (Y. C. Cheong et al.,2001). Abdominal adhesions formed after hernia repair can result inpain, bowel strangulation, infertility and in some cases death (Y. C.Cheong et al., 2001).

The sustained nature of the thrombotic and inflammatory response toinjury makes it desirable to provide a biomaterial that can reduce theincidence of inflammatory and foreign body responses after implantation.It would also be preferable to have a biomaterial that provides releaseof one or more therapeutic agents over a period of time in order tominimize such cell activated responses. Additionally, such a biomaterialwould also preferably be metabolized via a bioabsorption mechanism.

SUMMARY OF THE INVENTION

What is desired is a biomaterial (e.g., a coating or stand-alone film)that can be utilized alone or as a drug delivery carrier that preventsor diminishes chronic inflammation due to either the therapeutic agentor components of the coating. Furthermore, it is desirable that thebiomaterial release and deliver therapeutic agents in a sustained andcontrolled fashion to local tissue. The present invention is directedtoward various solutions that address this need.

What is also desired is a biomaterial (e.g., a coating or stand-alonefilm) that can be bioabsorbed by cells and that can deliver a drugwithout inducing chronic localized inflammation to tissues (e.g., theperitoneal or vascular tissue) that have been injured mechanically or byreperfusion injury, whereby the biomaterial (e.g., coating orstand-alone film) and the therapeutic agent are ingested and metabolizedby the cell, as it consumes the hydrolysis products of the biomaterialwith the drug.

In various aspects, the biomaterial is a coating for a medical device,or a stand alone film. The biomaterial can be a fatty acid-based,pre-cure-derived biomaterial. In various embodiments, the fattyacid-based, pre-cure-derived biomaterial is non-polymeric. In certaininstances, as described herein, the source of the fatty acid is an oil,e.g., a fish oil. In such an instance, the fatty acid-based,pre-cure-derived biomaterial can also be referred to as an “oil-based,pre-cure-derived biomaterial.”

In a particular aspect, the invention provides a fatty acid-based,pre-cure-derived biomaterial (e.g., coating or stand-alone film) thatcontains a pre-cure component. As described herein, a “pre-cure”component refers to fatty acids (e.g., from fish oil) that are partiallycured (using heat, UV, etc.) to induce an initial amount of fatty-acidoxidation and crosslinking to form a viscous fatty acid-derived gel. Thepre-cure component can be dissolved in a solvent, and sprayed onto adevice, e.g., a medical device. Once the pre-cure component isassociated with a medical device, the device can be used for treatmentin a subject, or it can be further exposed to additional curingconditions, which may result in a smooth, conformal coating referred toherein as a “fatty-acid based, pre-cure-derived biomaterial (coating).”The pre-cure and/or the fatty-acid based, pre-cure-derived biomaterialcan be characterized as a gel.

The pre-cured fatty acid component (also referred to herein as“pre-cured fatty acid component,” or simply “pre-cure;” when the sourceof the fatty acid is an oil, such as fish oil, it can also be referredto as “pre-cured oil”) can be added to a therapeutic agent, wherein thetherapeutic agent is optionally combined with an oil, and the resultingcombination can be further cured, thereby further cross-linking thefatty acids of the oil, to provide a fatty-acid based, pre-cure derivedbiomaterial, meaning a portion of the fatty acid-based biomaterial waspre-cured before formulation, and then exposed to further curing in thepresence of a therapeutic agent. In one embodiment, the fatty-acidbased, pre-cure derived biomaterial has tailored drug releaseproperties. When the resulting pre-cure-derived biomaterial is used as acoating for a medical device or as a stand-alone film, it may also bereferred to herein as a “fatty-acid based, pre-cure-derived coating” ora “fatty-acid based, pre-cure-derived stand-alone film.”

The process of creating a pre-cure (e.g., of a fish oil) has theadvantage of creating an initial platform of oxidized fatty acidcross-links that will be hydrolyzed by human tissue. In someembodiments, portions of the pre-cure curing process can be done in theabsence of the therapeutic agent, enabling addition of the agent laterin the process. In such embodiments, the pre-cure process can beconducted at a temperature and/or over a time period that wouldotherwise have lead to degradation of a thermally/chemically sensitivetherapeutic agent of interest (e.g., a rapamycin or cyclosporinederivative), except that the agent is not present for such portions ofthe pre-cure process. This process results in a partially cross-linkedcomposition, with reduced oxidizable reactive sites (e.g., C═C bonds),that contains no therapeutic agent. After the pre-cure is formed, thetherapeutic agent is then added, and optionally vitamin E is also added.The vitamin E component has the advantage of protecting the drug andpre-cured oil from further oxidation, but does not inhibit furthercross-linking (e.g., esterification) of the fatty acid and/or glyceridecomponents of the oil.

Accordingly, in various aspects, the present invention provides methodsfor producing a hydrophobic, cross-linked, pre-cure-derived biomaterial,wherein the pre-cure-derived biomaterial is utilized with one or moretherapeutic agents, wherein the therapeutic agents have a controlledloading and are released in a sustained manner as the coating isabsorbed. In various embodiments, provided are methods of tailoring thedrug release profile of a pre-cure-derived biomaterial by control of thecuring conditions used to produce the pre-cure-derived biomaterial(e.g., coating or stand-alone film) from an oil containing startingmaterial, the use of a free radical scavenger in an oil containingstarting material from which the pre-cure-derived biomaterial is formed,or combinations thereof. In various embodiments, the methods of thepresent invention tailor the drug release properties of a fatty-acidbased, pre-cure-derived biomaterial (e.g., coating or stand-alone film)by controlling the degree of cross-linking of fatty acids. In variousembodiments, the methods of the present invention tailor the drugdelivery properties of a pre-cure-derived biomaterial (e.g., coating orstand-alone film) by controlling the level of fatty acids, tocopherols,lipid oxidation products, and soluble components in the fattyacid-based, pre-cure-derived biomaterial.

In various aspects, the present invention may provide fatty acid-derivedbiomaterials with a pre-cured oil component (e.g., coating orstand-alone film) comprising one or more therapeutic agents with atailored release profile for one or more of the therapeutic agents. Sucha material is referred to herein as a “fatty acid-based,pre-cure-derived biomaterial.” In various embodiments, the tailoredrelease profile comprises a sustained release profile. In variousembodiments, the tailored release profile properties are controlled bythe level of fatty acids, tocopherols, lipid oxidation products, andsoluble components in the fatty acid-based, pre-cure-derivedbiomaterial. In various aspects of the present invention, the fattyacid-based, pre-cure-derived biomaterial contains fatty acids, many ofwhich originate as triglycerides. It has previously been demonstratedthat triglyceride byproducts, such as partially hydrolyzed triglyceridesand fatty acid molecules can integrate into cellular membranes andenhance the solubility of drugs into cellular membranes (M. Cote, J. ofControlled Release. 2004, Vol. 97, pgs 269-281; C. P. Burns et al.,Cancer Research. 1979, Vol. 39, pgs 1726-1732; R. Beck et al., Circ.Res. 1998, Vol 83, pgs 923-931; B. Henning et al. Arterioscler. Thromb.Vasc. Biol. 1984, Vol 4, pgs 489-797). Whole triglycerides are known notto enhance cellular uptake as well as a partially hydrolyzedtriglyceride, because it is difficult for whole triglycerides to crosscell membranes due to their relatively larger molecular size. Vitamin Ecompounds can also integrate into cellular membranes resulting indecreased membrane fluidity and cellular uptake (P. P. Constantinides.Pharmaceutical Research. 2006; Vol. 23, No. 2, 243-255).

In various aspects, the present invention may provide a pre-cure-derivedbiomaterial (e.g., coating or stand-alone film) containing fatty acids,glycerides, lipid oxidation products and alpha-tocopherol in differingamounts and ratios to contribute to a fatty acid-based, pre-cure-derivedbiomaterial in a manner that provides control over the cellular uptakecharacteristics of the fatty acid-based, pre-cure-derived biomaterialand any therapeutic agents mixed therein.

In various aspects, the present invention may provide coated medicaldevices having a fatty acid-based, pre-cure-derived biomaterial drugrelease coating comprising one or more layers of said pre-cure-derivedbiomaterial, wherein at least one of the pre-cure-derived biomateriallayers contains one or more therapeutic agents. The coating can be ahydrophobic, cross-linked pre-cure-derived biomaterial (derived, e.g.,from fish oil, making it an “oil-derived, pre-cure-derivedbiomaterial”). In various embodiments, the coating is non-polymeric. Invarious embodiments, the drug release coating hydrolyzes in vivo, intosubstantially non-inflammatory compounds. In various embodiments, thepre-cure-derived biomaterial is coated onto a medical device that isimplantable in a patient to effect long term local delivery of thetherapeutic agent to the patient. In various embodiments the delivery isat least partially characterized by the total and relative amounts ofthe therapeutic agent released over time. In various embodiments, thetailored delivery profile is controlled by the level of lipid oxidation,vitamin E and/or soluble components in the fatty acid-based,pre-cure-derived biomaterial. In various embodiments, the deliveryprofile is a function of the solubility and lipophilicity of the coatingcomponents and therapeutic agent in-vivo. The pre-cure-derivedbiomaterial can be a stand-alone film, gel, suspension, or emulsion thathas the properties discussed above.

In various embodiments, the present invention may provide fatty-acidbased, pre-cure-derived coatings where the drug release profile of thecoating is tailored through the provision of two or more coatings andselection of the location of the therapeutic agent. The drug locationcan be altered, e.g., by coating a bare portion of a medical device witha first starting material and creating a first cured coating, thencoating at least a portion of the first cured-coating with the drug-oilformulation to create a second overlayer coating. It is to be understoodthat the process of providing two layers can be extended to providethree or more layers, wherein at least one of the layers comprises afatty acid-based, pre-cure-derived biomaterial. In addition, one or moreof the layers can be drug releasing, and the drug release profile ofsuch layers can be tailored using the methods described herein.

In accordance with various embodiments of the present invention, thepre-cure-derived biomaterial (e.g., coating or stand-alone film)contains lipids. The pre-cure-derived biomaterial can be formed from anoil, such as fish oil, starting material. The pre-cure-derivedbiomaterial (e.g., coating or stand-alone film) can contain saturated,unsaturated, or polyunsaturated fatty acids. When the fatty acid-based,pre-cure-derived biomaterial is cross-linked, it can contain omega-3fatty acids. The fatty acid-based, pre-cure-derived biomaterial can alsocontain alpha-tocopherol, or vitamin E derivatives, and/or a therapeuticagent.

The coatings of the present invention can be formulated to contain avariety of other chemicals and entities in addition to a therapeuticagent, including, but not limited to, one or more of: a pharmaceuticallyacceptable carrier, an excipient, a surfactant, a binding agent, anadjuvant agent, and/or a stabilizing agent (including preservatives,buffers and antioxidants). In one embodiment, alpha-tocopherol TPGS maybe added to the coatings of the present invention.

In various aspects, the present invention may provide methods fortreating injury in a mammal, such as, e.g., a human. In variousembodiments, the injury is a vascular injury. In various embodiments,the methods comprise locally administering one or more therapeuticagents in a therapeutically effective amount by sustained release of theone or more therapeutic agents from a coating comprising a fattyacid-based, pre-cure-derived biomaterial.

The teachings herein demonstrate that the cured coatings and stand-alonefilms that comprise a fatty acid-based, pre-cure-derived biomaterialprovide the ability to regulate the release profile of drug-loaded fattyacid-based, pre-cure-derived biomaterials from the films or fromimplantable devices. In various embodiments, the release profile can becontrolled through changes in oil chemistry by varying fatty acid-based,pre-cure-derived biomaterial (e.g., coating or stand-alone film)composition and cure times. The teachings demonstrate that the releaseof therapeutic compounds from pre-cure-derived biomaterials (e.g.,coating or stand-alone film) can be modified based on altering the oilcuring conditions, the oil starting material, length of curing, andamount of cross-linking. The teachings demonstrate that thecross-linking and gelation of the fatty-acid based, pre-cure-derived oilcoatings and fatty-acid based, pre-cure-derived stand-alone films can bedirectly dependent on the formation of hydroperoxides in the oilcomponent, which increases with increasing temperature and degree ofunsaturation of the oil. Dissolution experiments have shown that drugrelease and coating degradation are more rapid for the cross-linkedcoatings produced using lower temperature curing conditions (e.g.,around 150° F.) than higher temperature curing conditions (e.g., around200° F.).

In another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device, comprising a cross-linkedfish oil. The fish oil can optionally include a therapeutic agent. Thecoating can be prepared according to the methods described herein, suchthat, when the coating does include a therapeutic agent, the coatingreleases the therapeutic agent at a desired release rate in vivo.

In another aspect, the invention provides a coating for a medicaldevice, comprising a fatty acid and a therapeutic agent, wherein thefatty acid was partially cross-linked before association with thetherapeutic agent. That is, the fatty acid was partially cured to inducean initial amount of fatty-acid cross-linking, and then combined withthe therapeutic agent. The resulting composition can then be exposed toan additional curing procedure, e.g., after being applied to a medicaldevice, thereby further cross-linking the fatty acids to form a coating.In one embodiment, the therapeutic agent is contained within the coatingin such a manner that the therapeutic agent has an enhanced releaseprofile. As used herein, the phrase “enhanced release profile” refers tothe release profile of a therapeutic agent by a pre-cure-derivedbiomaterial that is prepared using the methods of the current invention.That is, as discussed herein, by preparing a pre-cure, adding atherapeutic agent to the pre-cure, and further curing the therapeuticagent-pre-cure composition, a therapeutic cross-linked biomaterial iscreated that will release the therapeutic agent in a manner differentfrom a preparation that was not prepared according to the methods of theinvention (i.e., a fatty acid-derived biomaterial that was not preparedwith the use of a pre-cure composition).

For example, by first preparing a pre-cure in the absence of atherapeutic agent, the therapeutic agent is not exposed to processconditions that would otherwise lead to its degradation. The therapeuticagent can then be added to the pre-cure for further processing. Becauseof this preservation of the therapeutic agent structure, there is lessdegradation of the therapeutic agent during manufacturing of thecoating. Accordingly, there exists a higher amount of therapeutic agentin the coating that can be released, especially compared to a coatingthat was prepared without a pre-cure (i.e., compared to a coating inwhich the uncured, fatty-acid containing material is first combined witha therapeutic agent, and then cured). Thus, the therapeutic agent'srelease profile is “enhanced.”

In one embodiment, the coating of the invention further comprises apre-cured glyceride. The coating can comprise 5-25% C₁₄ fatty acidsand/or 5-30% C₁₆ fatty acids. The coating can be configured to produce aglyceride upon metabolization in-vivo. The coating can compriseapproximately 30-90% saturated fatty acids; approximately 30-80%unsaturated fatty acids; a glyceride; one or more of the groupconsisting of a glyceride, a glycerol, and a fatty alcohol, any of whichcan be partially cross-linked; and/or vitamin E.

In another embodiment, the coating is associated with an implantabledevice. The coating can be associated with a medical device, and themedical device is a stent, a catheter, a surgical mesh, or a balloon.

In one embodiment, the therapeutic agent that is associated with thecoating is an anti-proliferative drug, an anti-inflammatory agent, anantimicrobial agent or antibiotic agent. In another embodiment, thetherapeutic agent is Compound A, Compound B, Compound C, Compound D,Compound E (as described below), a cyclosporine derivative or rapamycinderivative.

In another embodiment, the coating has a release profile of thetherapeutic agent in 0.01 M phosphate buffered saline (PBS) out to about5-20 days. The coating can release said therapeutic agent at a desiredrelease rate in vivo. In one embodiment, the coating has a releaseprofile of the therapeutic agent in 0.01 M phosphate buffered saline(PBS) out to more than 20 days.

In another embodiment, the coating comprises approximately 10-20% C₁₄saturated fatty acids and approximately 25-50% C₁₆ saturated fattyacids. The coating can comprise lactone and ester cross links. Thecoating can contain disordered hydrocarbon chains as determined byinfrared absorption and X-ray diffraction.

In another embodiment, the coating does not contain a cross-linkingagent.

In still another embodiment, the coating hydrolyzes in vivo into fattyacids, glycerols, and glycerides; hydrolyzes in vivo intonon-inflammatory components; and/or contains an amount of carboxylicacid groups sufficient to facilitate hydrolysis in vivo.

The coating can comprises approximately 50-90% saturated fatty acids;approximately 10-50% unsaturated fatty acids; a glyceride; and/or one ormore of the group consisting of a glyceride, a glycerol, and a fattyalcohol, any of which can be partially cross-linked. In one embodiment,the source of the fatty acids is an oil, such as oil is a fish oil,olive oil, grape oil, palm oil, or flaxseed oil. In one embodiment, thesource is a fish oil.

In another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device, comprising: a pre-cured,cross-linked fatty acid, comprising approximately 5-50% C₁₆ fatty acids.

In still another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device comprising anon-polymeric, cross-linked fatty acid, comprising approximately 5-25%C₁₄ fatty acids and 5-50% C₁₆ fatty acids.

In another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device comprising cross-linkedfatty acids and glycerides, wherein the fatty acids and glycerides havedisordered alkyl groups, which cause the coating to be flexible andhydratable.

In yet another aspect, the invention provides a fatty-acid based,pre-cure-derived for a medical device comprising a fatty acid-derivedbiomaterial, wherein the fatty acid-derived biomaterial comprisesdelta-lactones.

In still another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device, wherein the coatingcomprises lactone and ester cross links, as indicated by an infraredabsorption spectrum having peaks at approximately 1740-1850 cm⁻¹,respectively.

In another aspect, the invention provides a fatty-acid based,pre-cure-derived coating for a medical device, comprising across-linked, fatty acid-derived biomaterial, wherein approximately60-90% of the biomaterial is constituted by fatty acids with molecularweights below 500.

In yet another aspect, the invention provides a fatty-acid based,pre-cure-derived biomaterial suitable for achieving modulated healing ina tissue region in need thereof, wherein the biomaterial is administeredin an amount sufficient to achieve said modulated healing, wherein themodulated healing comprises a modulation of platelet or fibrindeposition in or near said tissue region. In one embodiment, the tissueregion is the vasculature of a subject.

In still another aspect, the invention provides a fatty-acid based,pre-cure-derived biomaterial suitable for achieving modulated healing ata site of vascular injury in need thereof, wherein the composition isadministered in an amount sufficient to achieve said modulated healing,wherein the modulated healing comprises a modulation of at least onemetric of organized tissue repair. In one embodiment, the vascularhealing is the inflammatory stage of vascular healing. In anotherembodiment, the organized tissue repair comprises platelet or fibrindeposition at the site of vascular injury. In another embodiment, themodulation of at least one metric of organized tissue repair is a delayin the healing process at a site of vascular injury.

In another embodiment, the biomaterials of the invention areadministered to the region in need thereof via a catheter, balloon,stent, surgical mesh, surgical dressing, or graft.

In another aspect, provided herein is a preparation for deriving acoating for a medical device, the preparation comprising:

a pre-cured cross-linked fatty acid oil, wherein the coating containsester and lactone cross-links, and wherein a portion of the preparationcomprises a pre-cured natural oil. The preparation can further comprisea therapeutic agent. The preparation has a viscosity of about 1.0×10⁵ toabout 1.0×10⁷ cps. The preparation can be further dissolved in anorganic solvent.

Also provided herein is a method for producing a fatty-acid based,pre-cure-derived coating for a medical device, wherein the methodcomprises:

curing an oil-containing starting material according to a first curingcondition to form a second material;

combining a therapeutic agent with the second material to form a thirdmaterial;

and curing the third material such that a coating is produced.

In one embodiment of the method, the therapeutic agent is combined withan oil-containing material or organic solvent before combining with thesecond material. In another embodiment, the curing temperature of thefirst curing condition and/or total curing duration exceed thedegradation temperature of the therapeutic agent. In still anotherembodiment, the first curing condition results in appreciable formationof esters and lactones in the oil such that substantial cross linking offatty acids occurs during the second curing condition. In still anotherembodiment, the curing temperature and duration is adjusted to tailorthe release profile of the therapeutic agent. Vitamin E can be added tothe second material. In another embodiment, the third material iscombined with an organic solvent, and applied to a medical device beforecuring to form a conformal coating. The third material can then besprayed on a medical device before curing to form a coating, e.g., anon-conformal coating. In another embodiment of the method, theoil-containing starting material is fish oil. In still anotherembodiment of the method, the medical device is a stent, a catheter, asurgical mesh or a balloon.

The second material produced by the method can have a viscosity of about1.0×10⁵ to about 1.0×10⁷ cps.

The therapeutic agent used in the method can be an anti-proliferativedrug or an anti-inflammatory agent. The therapeutic agent used in themethod can also be Compound A, Compound B, Compound C, Compound D,Compound E, a cyclosporine derivative or rapamycin derivative.

In another embodiment of the method, the first curing condition istailored such that the second material, when applied to a medicaldevice, provides a non-conformal coating on the medical device; andwherein the second curing condition is tailored such that the thirdmaterial, when applied to a coating, provides a conformal coating. Inanother embodiment, the curing time for the first curing condition canbe substantially increased in order to reduce the curing time requiredfor the second curing condition to obtain desired mechanical propertiesof the final coating. In another embodiment, the first curing conditioncan be substantially increased in order to reduce the curing timerequired for the second curing condition to obtain desired mechanicalproperties and preserve a thermally sensitive drug to the final coating.

In another aspect, provided herein is a fatty-acid based,pre-cure-derived coating for a medical device, wherein said coatingcomprises: a hydrophobic, non-polymeric cross-linked fish oil; and atherapeutic agent; wherein the coating can withstand 16-22 psi ofcompressive force.

In still another aspect, provided herein is a fatty-acid based,pre-cure-derived medical device coating, that hydrolyzes in vivo intofatty acids, glycerols, and glycerides.

In yet another aspect, provided herein is a fatty-acid based,pre-cure-derived coating for a medical device, comprising: anon-polymeric, partially cross-linked fatty acid, and a therapeuticagent, wherein the therapeutic agent is contained within the coating insuch a manner that the therapeutic agent has an enhanced releaseprofile.

In another aspect, provided herein is a preparation for deriving acoating for a medical device, the preparation comprising: anon-polymeric, partially cross-linked fatty acid, and a therapeuticagent, wherein the coating contains ester and lactone cross-links.

In still another aspect, provided herein is a fatty-acid based,pre-cure-derived coating for a medical device, comprising: across-linked fatty acid oil, and a therapeutic agent; wherein thecoating is prepared by curing a natural oil-containing starting materialto induce cross-linking of a portion of the fatty acids; adding atherapeutic agent to the partially-cross linked fatty acid oil to form atherapeutic agent-oil composition; and curing the therapeutic agent-oilcomposition to induce additional cross links in the fatty acids, suchthat the coating is formed. In one embodiment of the coating, thetherapeutic agent is combined with a natural oil-containing material,organic solvent and/or vitamin E before combining with thepartially-cross linked fatty acid oil. In another embodiment, thetherapeutic agent is combined with vitamin E before combining with thepartially-cross linked fatty acid oil, such that the therapeutic agenthas an enhanced release profile.

In another aspect, provided herein is a stand-alone film comprising apre-cured fatty acid. The stand-alone film can comprise approximately5-50% C₁₆ fatty acids; 5-25% C₁₄ fatty acids, 5-40% C₁₆ fatty acids;and/or vitamin E. The film can be bioabsorbable, and/or maintainanti-adhesive properties. The stand-alone film can further comprise atherapeutic agent, such as Compound A, Compound B, Compound C, CompoundD, Compound E, a cyclosporine derivative or rapamycin derivative. Thetherapeutic agent can be combined with the fatty acid compound prior toformation of the film, resulting in the therapeutic agent beinginterspersed throughout the film.

In another aspect, provided herein is a stand-alone film, comprising:

a cross-linked fatty acid oil, and a therapeutic agent;

wherein the stand-alone film is prepared by curing a naturaloil-containing starting material to induce cross-linking of a portion ofthe fatty acids;

adding a therapeutic agent to the partially-cross linked fatty acid oilto form a therapeutic agent-oil composition; and

curing the therapeutic agent-oil composition to induce additional crosslinks in the fatty acids, such that the stand-alone film is formed.

In another aspect, provided herein is a fatty-acid based,pre-cure-derived biomaterial comprising a partially cross-linked fattyacid and a therapeutic agent, wherein the therapeutic agent comprises atleast 40%, by weight, of the biomaterial composition. In anotherembodiment, the therapeutic agent comprises at least 50%, by weight, ofthe biomaterial composition.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects, embodiments, objects, features andadvantages of the invention can be more fully understood from thefollowing description in conjunction with the accompanying drawings. Inthe drawings, like reference characters generally refer to like featuresand structural elements throughout the various figures. The drawings arenot necessarily to scale, emphasis instead being placed uponillustrating the principles of the invention.

FIG. 1 is a schematic illustration of an example of the creation ofperoxide and ether cross-linking in a polyunsaturated oil;

FIG. 2 is a schematic illustration of an example of the creationcarbon-carbon cross-linking in a polyunsaturated oil (Diels-Alder typereaction);

FIG. 3 shows the mechanism for the formation of the hydrophobicpre-cured-derived biomaterial coating;

FIG. 4 shows a summary of pre-cured-derived biomaterial reactionchemistry;

FIG. 5 is a schematic of reactions of oils that result in the formationof ester groups;

FIG. 6 schematically depicts the hydrolysis of the ester links in atriglyceride;

FIG. 7 shows bar graphs showing similarity of fatty acid compositionbetween fatty-acid based, pre-cure-derived biomaterial coating andbiological tissue;

FIG. 8 is a flow chart illustrating a method of making the coatedmedical device of the present invention, in accordance with oneembodiment of the present invention;

FIG. 9 is a flow chart illustrating a variation of the method of FIG. 8,in accordance with one embodiment of the present invention;

FIGS. 10A-10E are various images of coated medical devices;

FIG. 11 provides the GC-FID fatty acid profile from a 0.1 M PBS solutionafter 30 day exposure of a totally cured biomaterial (no pre-curecomponent) as described in Example 1;

FIG. 12 shows the fatty acid profile chromatogram acquired for atherapeutic agent/biomaterial formulation sprayed on coupons with andwithout final curing;

FIG. 13 depicts a flow diagram presenting the process to create afatty-acid based, pre-cure-derived coating on a stent loaded with atherapeutic is outlined in Example 2; and

FIG. 14 shows the drug release profile for a cured oil therapeuticcoating in 0.01 M PBS buffer as described in Example 2;

FIG. 15 shows the drug release profile for the fatty-acid based,pre-cure-derived biomaterial described in Example 3;

FIG. 16 shows trackability force data for the fatty-acid based,pre-cure-derived biomaterial described in Example 4;

FIG. 17 shows assay recovery results from Co—Cr stents as a function offinal cure time;

FIG. 18 shows the drug recovery for the fatty-acid based,pre-cure-derived biomaterial described in Example 4;

FIG. 19 shows the viscosity of the pre-cure-derived biomaterialdescribed in Example 6A;

FIGS. 20A and 20B are SEMs of stents coated with a pre-cure-derivedbiomaterial;

FIGS. 21A, 21B, and 21C shows FTIR analysis of pre-cured fish oil beforeand after curing;

FIG. 22 shows GC fatty acid profile data acquired for a pre-cure fishoil sprayed onto coupons in MTBE before and after final curing;

FIG. 23 shows a fatty acid profile chromatogram acquired for partiallycured (i.e., pre-cure) fish oil sprayed onto coupons in MTBE before andafter final curing;

FIGS. 24A, 24B and 24C shows FTIR spectra of vitamin E dissolved in MTBEand sprayed onto coupons with and without final curing;

FIGS. 25A, 25B and 25C show HPLC chromatograms of a vitamin E controloverlaid with vitamin E sprayed onto coupons before and after curing;

FIGS. 26A, 26B and 26C show FTIR analysis of a therapeutic agent afterspraying onto coupons before and after curing;

FIGS. 27A, 27B and 27C show HPLC chromatograms of a therapeutic agentafter spraying onto coupons before and after curing;

FIGS. 28A, 28B and 28C presents the FTIR spectra of the Compound B fattyacid-derived, pre-cured biomaterial coating before and after finalcuring;

FIGS. 29A and 29B show HPLC chromatograms of Compound B control overlaidwith the Compound B assay results obtained from a pre-cure derivedbiomaterial after final curing;

FIG. 30 shows fatty acid profile data acquired for a therapeuticagent/biomaterial formulation sprayed on coupons with and without finalcuring;

FIGS. 31A, 31B and 31C show FTIR spectra of a therapeutic agent in 75:25pre-cured fish oil: vitamin E sprayed onto stents and cured at varioustimes; and

FIGS. 32, 33 and 34 show results from the in vivo experiments describedin Example 15.

DETAILED DESCRIPTION

The present invention is directed toward the formation of a fatty-acidbased, pre-cure-derived biomaterial that can be utilized alone or incombination with a medical device for the release and local delivery ofone or more therapeutic agents, methods of forming and tailoring theproperties of said coatings and methods of using said coatings fortreating injury in a mammal. Additionally, due to the unique propertiesof the underlying chemistry of the biomaterial, it will be demonstratedthat the coating contains specific chemical components that assist inreducing a foreign body response and inflammation at the site of tissueinjury during implantation that improves its in-vivo performance. Thefatty-acid based, pre-cure-derived biomaterial can be formed from apre-cure, e.g., a pre-cured fatty acid.

Prior to further describing the invention, it may be helpful togenerally and briefly describe injury and the biological responsethereto.

Vascular Injury

Vascular injury causing intimal thickening can be broadly categorized asbeing either biologically or mechanically induced. Biologically mediatedvascular injury includes, but is not limited to, injury attributed toinfectious disorders including endotoxins and herpes viruses, such ascytomegalovirus; metabolic disorders, such as atherosclerosis; andvascular injury resulting from hypothermia, and irradiation.Mechanically mediated vascular injury includes, but is not limited to,vascular injury caused by catheterization procedures or vascularscraping procedures, such as percutaneous transluminal coronaryangioplasty; vascular surgery; transplantation surgery; laser treatment;and other invasive procedures which disrupt the integrity of thevascular intima or endothelium. Generally, neointima formation is ahealing response to a vascular injury.

Inflammatory Response

Wound healing upon vascular injury occurs in several stages. The firststage is the inflammatory phase. The inflammatory phase is characterizedby hemostasis and inflammation. Collagen exposed during wound formationactivates the clotting cascade (both the intrinsic and extrinsicpathways), initiating the inflammatory phase. After injury to tissueoccurs, the cell membranes, damaged from the wound formation, releasethromboxane A2 and prostaglandin 2-alpha, which are potentvasoconstrictors. This initial response helps to limit hemorrhage. Aftera short period, capillary vasodilatation occurs secondary to localhistamine release, and the cells of inflammation are able to migrate tothe wound bed. The timeline for cell migration in a normal wound healingprocess is predictable. Platelets, the first response cell, releasemultiple chemokines, including epidermal growth factor (EGF),fibronectin, fibrinogen, histamine, platelet-derived growth factor(PDGF), serotonin, and von Willebrand factor. These factors helpstabilize the wound through clot formation. These mediators act tocontrol bleeding and limit the extent of injury. Platelet degranulationalso activates the complement cascade, specifically C5a, which is apotent chemoattractant for neutrophils.

As the inflammatory phase continues, more immune response cells migrateto the wound. The second response cell to migrate to the wound, theneutrophil, is responsible for debris scavenging, complement-mediatedopsonization of bacteria, and bacteria destruction via oxidative burstmechanisms (i.e., superoxide and hydrogen peroxide formation). Theneutrophils kill bacteria and decontaminate the wound from foreigndebris.

The next cells present in the wound are the leukocytes and themacrophages (monocytes). The macrophage, referred to as theorchestrator, is essential for wound healing. Numerous enzymes andcytokines are secreted by the macrophage. These include collagenases,which debride the wound; interleukins and tumor necrosis factor (TNF),which stimulate fibroblasts (produce collagen) and promote angiogenesis;and transforming growth factor (TGF), which stimulates keratinocytes.This step marks the transition into the process of tissuereconstruction, i.e., the proliferative phase.

Cell Proliferation

The second stage of wound healing is the proliferative phase.Epithelialization, angiogenesis, granulation tissue formation, andcollagen deposition are the principal steps in this anabolic portion ofwound healing. Epithelialization occurs early in wound repair. At theedges of wounds, the epidermis immediately begins thickening. Marginalbasal cells begin to migrate across the wound along fibrin strandsstopping when they contact each other (contact inhibition). Within thefirst 48 hours after injury, the entire wound is epithelialized.Layering of epithelialization is re-established. The depths of the woundat this point contain inflammatory cells and fibrin strands. Agingeffects are important in wound healing as many, if not most, problemwounds occur in an older population. For example, cells from olderpatients are less likely to proliferate and have shorter life spans andcells from older patients are less responsive to cytokines.

Heart disease can be caused by a partial vascular occlusion of the bloodvessels that supply the heart, which is preceded by intimal smoothmuscle cell hyperplasia. The underlying cause of the intimal smoothmuscle cell hyperplasia is vascular smooth muscle injury and disruptionof the integrity of the endothelial lining. Intimal thickening followingarterial injury can be divided into three sequential steps: 1)initiation of smooth muscle cell proliferation following vascularinjury, 2) smooth muscle cell migration to the intima, and 3) furtherproliferation of smooth muscle cells in the intima with deposition ofmatrix. Investigations of the pathogenesis of intimal thickening haveshown that, following arterial injury, platelets, endothelial cells,macrophages and smooth muscle cells release paracrine and autocrinegrowth factors (such as platelet derived growth factor, epidermal growthfactor, insulin-like growth factor, and transforming growth factor) andcytokines that result in the smooth muscle cell proliferation andmigration. T-cells and macrophages also migrate into the neointima. Thiscascade of events is not limited to arterial injury, but also occursfollowing injury to veins and arterioles.

Granulomatous Inflammation

Chronic inflammation, or granulomatous inflammation, can cause furthercomplications during the healing of vascular injury. Granulomas areaggregates of particular types of chronic inflamatory cells which formnodules in the millimeter size range. Granulomas may be confluent,forming larger areas. Essential components of a granuloma arecollections of modified macrophages, termed epithelioid cells, usuallywith a surrounding zone of lymphocytes. Epithelioid cells are so namedby tradition because of their histological resemblance to epithelialcells, but are not in fact epithelial; they are derived from bloodmonocytes, like all macrophages. Epithelioid cells are less phagocyticthan other macrophages and appear to be modified for secretoryfunctions. The full extent of their functions is still unclear.Macrophages in granulomas are commonly further modified to formmultinucleate giant cells. These arise by fusion of epithelioidmacrophages without nuclear or cellular division forming huge singlecells which may contain dozens of nuclei. In some circumstances thenuclei are arranged round the periphery of the cell, termed aLanghans-type giant cell; in other circumstances the nuclei are randomlyscattered throughout the cytoplasm (i.e., the foreign body type of giantcell which is formed in response to the presence of other indigestibleforeign material in the tissue). Areas of granulomatous inflammationcommonly undergo necrosis.

Formation of granulomatous inflammation seems to require the presence ofindigestible foreign material (derived from bacteria or other sources)and/or a cell-mediated immune reaction against the injurious agent (typeIV hypersensitivity reaction).

Drug Eluting, Fatty-Acid Based, Pre-Cure-Derived Biomaterials: Coatingsand Stand-Alone Films

The fatty-acid based, pre-cure-derived biomaterials (e.g., coatings andstand-alone films) of the present invention comprise a hydrophobiccross-linked fatty acid-derived biomaterial and optionally one or moretherapeutic agents contained in the fatty-acid based, pre-cure-derivedbiomaterial. In addition, the pre-cure-derived biomaterials (e.g.,coatings and stand-alone films) of the present invention arebio-absorbable as described herein. The therapeutic agent can be anactive agent as contained in the coating and/or a prodrug that, e.g.,becomes active once released from the coating. In one embodiment of theinvention, the drug eluting pre-cure-derived biomaterial comprised of across-linked fatty acid, e.g., an omega-3 fatty acid. The cross-linkedfatty acid can be non-polymeric. The source of the omega-3 fatty acidcan be a naturally occurring oil, e.g., a fish oil.

The hydrophobic pre-cure-derived pre-cure biomaterial coatings andstand-alone films of the present invention may be formed from an oilcomponent. The oil component can be either an oil, or an oilcomposition. The oil component can be a synthetic oil, or a naturallyoccurring oil, such as fish oil, cod liver oil, flaxseed oil, grape seedoil, or other oils having desired characteristics. One embodiment of thepresent invention makes use of a fish oil in part because of the highcontent of omega-3 fatty acids. The fish oil can also serve as ananti-adhesion agent. In addition, the fish oil maintainsanti-inflammatory or non-inflammatory properties as well. The presentinvention is not limited to formation of the pre-cure-derivedbiomaterials with fish oil as the oil starting material. However, thefollowing description makes reference to the use of fish oil as oneexample embodiment. Other naturally occurring oils can be utilized inaccordance with the present invention as described herein.

It should be noted that as utilized herein, the term fish oil fatty acidincludes, but is not limited to, omega-3 fatty acid, oil fatty acid,free fatty acid, monoglycerides, di-glycerides, or triglycerides, estersof fatty acids, or a combination thereof. The fish oil fatty acidincludes one or more of arachidic acid, gadoleic acid, arachidonic acid,eicosapentaenoic acid, docosahexaenoic acid or derivatives, analogs andpharmaceutically acceptable salts thereof.

Furthermore, as utilized herein, the term free fatty acid includes butis not limited to one or more of butyric acid, caproic acid, caprylicacid, capric acid, lauric acid, myristic acid, palmitic acid,palmitoleic acid, stearic acid, oleic acid, vaccenic acid, linoleicacid, alpha-linolenic acid, gamma-linolenic acid, behenic acid, erucicacid, lignoceric acid, analogs and pharmaceutically acceptable saltsthereof. The naturally occurring oils, including fish oil, are cured asdescribed herein to form a hydrophobic cross-linked fatty acid-derivedpre-cure biomaterial, creating the coating.

The present invention relates to a bio-absorbable medical devicecoatings and stand-alone films that can exhibit anti-inflammatoryproperties, non-inflammatory properties, and anti-adhesion properties,and the corresponding method of making. The stand-alone film isgenerally formed of a naturally occurring oil, such as a fish oil. Inaddition, the oil composition can include a therapeutic agent component,such as a drug or other bioactive agent. The stand-alone film isimplantable in a patient for short term or long term applications. Asimplemented herein, the stand-alone film is a fatty-acid based,pre-cure-derived biomaterial derived at least in part from a fatty acidcompound, wherein the stand-alone film is prepared in accordance withthe methods of the invention. In accordance with further aspects of thepresent invention, the stand-alone film can further include a vitamin Ecompound forming a portion of the fatty acid compound.

In accordance with further aspects of the present invention, thestand-alone film further includes a therapeutic agent. The therapeuticagent can include an agent selected from the group consisting ofantioxidants, anti-inflammatory agents, anti-coagulant agents, drugs toalter lipid metabolism, anti-proliferatives, anti-neoplastics, tissuegrowth stimulants, functional protein/factor delivery agents,anti-infective agents, imaging agents, anesthetic agents,chemotherapeutic agents, tissue absorption enhancers, anti-adhesionagents, germicides, analgesics, prodrugs, and antiseptics.

In accordance with further aspects of the present invention, thetherapeutic agent is combined with the fatty acid compound prior toformation of the film, resulting in the therapeutic agent beinginterspersed throughout the film. Alternatively, the therapeutic agentis applied to the film in the form of a coating. In accordance withfurther aspects of the present invention, the stand-alone film isbioabsorbable. The stand-alone film can further maintain anti-adhesiveproperties.

In accordance with still another embodiment of the present invention, amethod of forming a stand-alone film is introduced. The method includesproviding a fatty acid compound in liquid form and applying the fattyacid compound to a substrate. The method also includes curing the fattyacid compound to form the stand-alone film. In accordance with oneaspect of the present invention, the substrate includes expandedpolytetrafluoroethylene (ePTFE) or polytetrafluoroethylene (PTFE). Inaccordance with further aspects of the present invention, the curingincludes using at least one curing method selected from a group ofcuring methods including application of UV light and application ofheat. The UV light can also be applied to set the fatty acid compound byforming a skin on the top surface of the fatty acid compound in liquidform prior to additional curing. In accordance with further aspects ofthe present invention, the substrate has an indentation that is used asa mold to shape the stand-alone film. Alternatively, the method canfurther include the step of cutting the film to a desirable shape.

The stand-alone film of the present invention may be used as a barrierto keep tissues separated to avoid adhesion. Application examples foradhesion prevention include abdominal surgeries, spinal repair,orthopedic surgeries, tendon and ligament repairs, gynecological andpelvic surgeries, and nerve repair applications. The stand-alone filmmay be applied over the trauma site or wrapped around the tissue ororgan to limit adhesion formation. The addition of therapeutic agents tothe stand-alone films used in these adhesion prevention applications canbe utilized for additional beneficial effects, such as pain relief orinfection minimization. Other surgical applications of the stand-alonefilm may include using a stand-alone film as a dura patch, buttressingmaterial, internal wound care (such as a graft anastomotic site), andinternal drug delivery system. The stand-alone film may also be used inapplications in transdermal, wound healing, and non-surgical fields. Thestand-alone film may be used in external wound care, such as a treatmentfor burns or skin ulcers. The stand-alone film may be used without anytherapeutic agent as a clean, non-permeable, non-adhesive,non-inflammatory, anti-inflammatory dressing, or the stand-alone filmmay be used with one or more therapeutic agents for additionalbeneficial effects. The stand-alone film may also be used as atransdermal drug delivery patch when the stand-alone film is loaded orcoated with one or more therapeutic agents.

Oils

With regard to the aforementioned oils, it is generally known that thegreater the degree of unsaturation in the fatty acids the lower themelting point of a fat, and the longer the hydrocarbon chain the higherthe melting point of the fat. A polyunsaturated fat, thus, has a lowermelting point, and a saturated fat has a higher melting point. Thosefats having a lower melting point are more often oils at roomtemperature. Those fats having a higher melting point are more oftenwaxes or solids at room temperature. Therefore, a fat having thephysical state of a liquid at room temperature is an oil. In general,polyunsaturated fats are liquid oils at room temperature, and saturatedfats are waxes or solids at room temperature.

Polyunsaturated fats are one of four basic types of fat derived by thebody from food. The other fats include saturated fat, as well asmonounsaturated fat and cholesterol. Polyunsaturated fats can be furthercomposed of omega-3 fatty acids and omega-6 fatty acids. Under theconvention of naming the unsaturated fatty acid according to theposition of its first double bond of carbons, those fatty acids havingtheir first double bond at the third carbon atom from the methyl end ofthe molecule are referred to as omega-3 fatty acids. Likewise, a firstdouble bond at the sixth carbon atom is called an omega-6 fatty acid.There can be both monounsaturated and polyunsaturated omega fatty acids.

Omega-3 and omega-6 fatty acids are also known as essential fatty acidsbecause they are important for maintaining good health, despite the factthat the human body cannot make them on its own. As such, omega-3 andomega-6 fatty acids must be obtained from external sources, such asfood. Omega-3 fatty acids can be further characterized as containingeicosapentaenoic acid (EPA), docosahexanoic acid (DHA), andalpha-linolenic acid (ALA). Both EPA and DHA are known to haveanti-inflammatory effects and wound healing effects within the humanbody.

As utilized herein, the term “bio-absorbable” generally refers to havingthe property or characteristic of being able to penetrate the tissue ofa patient's body. In certain embodiments of the present inventionbio-absorption occurs through a lipophilic mechanism. The bio-absorbablesubstance can be soluble in the phospholipid bi-layer of cells of bodytissue, and therefore impact how the bio-absorbable substance penetratesinto the cells.

It should be noted that a bio-absorbable substance is different from abiodegradable substance. Biodegradable is generally defined as capableof being decomposed by biological agents, or capable of being brokendown by microorganisms or biological processes. Biodegradable substancescan cause inflammatory response due to either the parent substance orthose formed during breakdown, and they may or may not be absorbed bytissues. Because the materials of the invention are biocompatible, andthey hydrolyze into non-inflammatory components, and are subsequentlybio-absorbed by surrounding tissue, they are referred to as“biomaterials.”

Drug Delivery

The pre-cure-derived biomaterials (e.g, coatings and stand-alone films)of the present invention deliver one or more therapeutic agents locallyto a targeted area using a stand-alone film, medical device or apparatusbearing the coating at a selected targeted tissue location of thepatient that requires treatment. The therapeutic agent is released fromthe biomaterial to the targeted tissue location. The local delivery of atherapeutic agent enables a more concentrated and higher quantity oftherapeutic agent to be delivered directly at the targeted tissuelocation, without having broader systemic side effects. With localdelivery, the therapeutic agent that escapes the targeted tissuelocation dilutes as it travels to the remainder of the patient's body,substantially reducing or eliminating systemic side effects.

Targeted local therapeutic agent delivery using a fatty-acid based,pre-cure-derived biomaterial (e.g, coatings and stand-alone films) canbe further broken into two categories, namely, short term and long term.The short term delivery of a therapeutic agent occurs generally within amatter of seconds or minutes to a few days or weeks. The long termdelivery of a therapeutic agent occurs generally within weeks to months.

The phrase “sustained release” as used herein generally refers to therelease of a biologically active agent that results in the long termdelivery of the active agent.

The phrase “controlled release” as used herein generally refers to therelease of a biologically active agent in a substantially predictablemanner over the time period of weeks or months, as desired andpredetermined upon formation of the biologically active agent on themedical device from which it is being released. Controlled releaseincludes the provision of an initial burst of release upon implantation,followed by the substantially predictable release over theaforementioned time period.

Drug Release Mechanisms

Prior attempts to create films and drug delivery platforms, such as inthe field of stents, primarily make use of high molecular weightsynthetic polymer based materials to provide the ability to bettercontrol the release of the therapeutic agent. Essentially, the polymerin the platform releases the drug or agent at a predetermined rate onceimplanted at a location within the patient. Regardless of how much ofthe therapeutic agent would be most beneficial to the damaged tissue,the polymer releases the therapeutic agent based on properties of thepolymer, e.g., diffusion in a biostable polymer and bulk erosion in abiodegradable polymeric material. Accordingly, the effect of thetherapeutic agent is substantially local at the surface of the tissuemaking contact with the medical device having the coating. In someinstances the effect of the therapeutic agent is further localized tothe specific locations of, for example, stent struts or mesh pressedagainst the tissue location being treated. High concentrations oftherapeutic agent present in tissue adjacent to a polymer that elicitsan inflammatory response can create the potential for a localized toxiceffect.

In various embodiments of the present invention, the fatty-acid based,pre-cure-derived biomaterial of the invention (e.g., coatings andstand-alone films) release one or more therapeutic agents by adissolution mechanism, e.g., dissolution of a therapeutic agentcontained in a soluble component of the coating into the medium incontact with the coating, (e.g., tissue), in addition to an erosionbased release mechanism. As a result, the drug release mechanism can bebased on the solubility of the therapeutic agent in the surroundingmedium. For example, a therapeutic agent near the interface between thehydrophobic coating and the surrounding medium can experience a chemicalpotential gradient that can motivate the therapeutic agent out of theoil based coating and into solution in the surrounding medium.Accordingly, in various embodiments, the release of a therapeutic agentis not rate-limited by the break-down or bulk erosion of the coating.

In various embodiments, the break-down products of the fatty-acid based,pre-cure-derived biomaterial of the invention are non-inflammatorybyproducts, e.g., free fatty acids and glycerides, that themselves canrelease one or more of the therapeutic agents via a dissolutionmechanism.

In various embodiments, the fatty-acid based, pre-cure derivedbiomaterial breaks-down according to a controlled surface erosionmechanism, thereby releasing one or more therapeutic agents to thesurrounding medium, e.g., tissue, via a dissolution mechanism.

Therapeutic Agents

As utilized herein, the phrase “therapeutic agent(s)” refers to a numberof different drugs or agents available, as well as future agents thatmay be beneficial for use with the fatty acid-derived, pre-curedbiomaterials (e.g., coatings and stand-alone films) of the presentinvention. The therapeutic agent component can take a number ofdifferent forms including anti-oxidants, anti-inflammatory agents,anti-coagulant agents, drugs to alter lipid metabolism,anti-proliferatives, anti-neoplastics, tissue growth stimulants,functional protein/factor delivery agents, anti-infective agents,anti-imaging agents, anesthetic agents, therapeutic agents, tissueabsorption enhancers, anti-adhesion agents, germicides, anti-septics,analgesics, prodrugs thereof, and any additional desired therapeuticagents such as those listed in Table 1 below.

TABLE 1 CLASS EXAMPLES Antioxidants Alpha-tocopherol, lazaroid,probucol, phenolic antioxidant, resveretrol, AGI-1067, vitamin EAntihypertensive Agents Diltiazem, nifedipine, verapamilAntiinflammatory Agents Glucocorticoids (e.g. dexamethazone,methylprednisolone), leflunomide, NSAIDS, ibuprofen, acetaminophen,hydrocortizone acetate, hydrocortizone sodium phosphate,macrophage-targeted bisphosphonates Growth Factor Angiopeptin, trapidil,suramin Antagonists Antiplatelet Agents Aspirin, dipyridamole,ticlopidine, clopidogrel, GP IIb/IIIa inhibitors, abcximab AnticoagulantAgents Bivalirudin, heparin (low molecular weight and unfractionated),wafarin, hirudin, enoxaparin, citrate Thrombolytic Agents Alteplase,reteplase, streptase, urokinase, TPA, citrate Drugs to Alter LipidFluvastatin, colestipol, lovastatin, atorvastatin, Metabolism (e.g.statins) amlopidine ACE Inhibitors Elanapril, fosinopril, cilazaprilAntihypertensive Agents Prazosin, doxazosin Antiproliferatives andCyclosporine, cochicine, mitomycin C, sirolimus Antineoplasticsmicophenonolic acid, rapamycin, everolimus, tacrolimus, paclitaxel,QP-2, actinomycin, estradiols, dexamethasone, methatrexate, cilostazol,prednisone, cyclosporine, doxorubicin, ranpirnas, troglitzon, valsarten,pemirolast, C- MYC antisense, angiopeptin, vincristine, PCNA ribozyme,2-chloro-deoxyadenosine, mTOR targeting compounds Tissue growthstimulants Bone morphogeneic protein, fibroblast growth factor Promotionof hollow Alcohol, surgical sealant polymers, polyvinyl particles, 2-organ occlusion or octyl cyanoacrylate, hydrogels, collagen, liposomesthrombosis Functional Protein/Factor Insulin, human growth hormone,estradiols, delivery nitric oxide, endothelial progenitor cellantibodies Second messenger Protein kinase inhibitors targetingAngiogenic Angiopoetin, VEGF Anti-Angiogenic Endostatin Inhibitation ofProtein Halofuginone, prolyl hydroxylase inhibitors, Synthesis/ECMformation C-proteinase inhibitors Antiinfective Agents Penicillin,gentamycin, adriamycin, cefazolin, amikacin, ceftazidime, tobramycin,levofloxacin, silver, copper, hydroxyapatite, vancomycin, ciprofloxacin,rifampin, mupirocin, RIP, kanamycin, brominated furonone, algaebyproducts, bacitracin, oxacillin, nafcillin, floxacillin, clindamycin,cephradin, neomycin, methicillin, oxytetracycline hydrochloride,Selenium. Gene Delivery Genes for nitric oxide synthase, human growthhormone, antisense oligonucleotides Local Tissue perfusion Alcohol, H2O,saline, fish oils, vegetable oils, liposomes Nitric oxide Donor NCX4016 - nitric oxide donor derivative of aspirin, Derivatives SNAP GasesNitric oxide, compound solutions Imaging Agents Halogenated xanthenes,diatrizoate meglumine, diatrizoate sodium Anesthetic Agents Lidocaine,benzocaine Descaling Agents Nitric acid, acetic acid, hypochloriteAnti-Fibrotic Agents Interferon gamma -1b, Interluekin - 10Immunosuppressive/Immunomodulatory Cyclosporine, rapamycin,mycophenolate motefil, Agents leflunomide, tacrolimus, tranilast,interferon gamma-1b, mizoribine, mTOR targeting compoundsChemotherapeutic Agents Doxorubicin, paclitaxel, tacrolimus, sirolimus,fludarabine, ranpirnase Tissue Absorption Fish oil, squid oil, omega 3fatty acids, vegetable oils, Enhancers lipophilic and hydrophilicsolutions suitable for enhancing medication tissue absorption,distribution and permeation Anti-Adhesion Hyaluronic acid, human plasmaderived surgical Agents sealants, and agents comprised of hyaluronateand carboxymethylcellulose that are combined with dimethylaminopropyl,ehtylcarbodimide, hydrochloride, PLA, PLGA Ribonucleases RanpirnaseGermicides Betadine, iodine, sliver nitrate, furan derivatives,nitrofurazone, benzalkonium chloride, benzoic acid, salicylic acid,hypochlorites, peroxides, thiosulfates, salicylanilide AntisepticsSelenium Analgesics Bupivicaine, naproxen, ibuprofen, acetylsalicylicacid

Some specific examples of therapeutic agents useful in theanti-restenosis realm include cerivastatin, cilostazol, fluvastatin,lovastatin, paclitaxel, pravastatin, rapamycin, a rapamycin carbohydratederivative (for example, as described in U.S. Pat. No. 7,160,867), arapamycin derivative (for example, as described in U.S. Pat. No.6,200,985), everolimus, seco-rapamycin, seco-everolimus, andsimvastatin. With systemic administration, the therapeutic agent isadministered orally or intravenously to be systemically processed by thepatient. However, there are drawbacks to a systemic delivery of atherapeutic agent, one of which is that the therapeutic agent travels toall portions of the patient's body and can have undesired effects atareas not targeted for treatment by the therapeutic agent. Furthermore,large doses of the therapeutic agent only amplify the undesired effectsat non-target areas. As a result, the amount of therapeutic agent thatresults in application to a specific targeted location in a patient mayhave to be reduced when administered systemically to reducecomplications from toxicity resulting from a higher dosage of thetherapeutic agent.

The term “mTOR targeting compound” refers to any compound that modulatesmTOR directly or indirectly. An example of an “mTOR targeting compound”is a compound that binds to FKBP 12 to form, e.g., a complex, which inturn inhibits phosphoinostide (PI)-3 kinase, that is, mTOR. In variousembodiments, mTOR targeting compounds inhibit mTOR. Suitable mTORtargeting compounds include, for example, rapamycin and its derivatives,analogs, prodrugs, esters and pharmaceutically acceptable salts.

Calcineurin is a serine/threonine phospho-protein phosphatase and iscomposed of a catalytic (calcineurin A) and regulatory (calcineurin B)subunit (about 60 and about 18 kDa, respectively). In mammals, threedistinct genes (A-alpha, A-beta, A-gamma) for the catalytic subunit havebeen characterized, each of which can undergo alternative splicing toyield additional variants. Although mRNA for all three genes appears tobe expressed in most tissues, two isoforms (A-alpha and A-beta) are mostpredominant in brain.

The calcineurin signaling pathway is involved in immune response as wellas apoptosis induction by glutamate excitotoxicity in neuronal cells.Low enzymatic levels of calcineurin have been associated with Alzheimersdisease. In the heart or in the brain calcineurin also plays a key rolein the stress response after hypoxia or ischemia.

Substances that are able to block the calcineurin signal pathway can besuitable therapeutic agents for the present invention. Examples of suchtherapeutic agents include, but are not limited to, FK506, tacrolimus,cyclosporin and include derivatives, analogs, esters, prodrugs,pharmaceutically acceptably salts thereof, and conjugates thereof whichhave or whose metabolic products have the same mechanism of action.Further examples of cyclosporin derivatives include, but are not limitedto, naturally occurring and non-natural cyclosporins prepared by total-or semi-synthetic means or by the application of modified culturetechniques. The class comprising cyclosporins includes, for example, thenaturally occurring Cyclosporins A through Z, as well as variousnon-natural cyclosporin derivatives, artificial or synthetic cyclosporinderivatives. Artificial or synthetic cyclosporins can includedihydrocyclosporins, derivatized cyclosporins, and cyclosporins in whichvariant amino acids are incorporated at specific positions within thepeptide sequence, for example, dihydro-cyclosporin D.

In various embodiments, the therapeutic agent comprises one or more of amTOR targeting compound and a calcineurin inhibitor. In variousembodiments, the mTOR targeting compound is a rapamycin or a derivative,analog, ester, prodrug, pharmaceutically acceptably salts thereof, orconjugate thereof which has or whose metabolic products have the samemechanism of action. In various embodiments, the calcineurin inhibitoris a compound of Tacrolimus, or a derivative, analog, ester, prodrug,pharmaceutically acceptably salts thereof, or conjugate thereof whichhas or whose metabolic products have the same mechanism of action or acompound of Cyclosporin or a derivative, analog, ester, prodrug,pharmaceutically acceptably salts thereof, or conjugate thereof whichhas or whose metabolic products have the same mechanism of action.

The therapeutic agents that can be used with the fatty acid-derived,pre-cured biomaterials of the invention can also include antimicrobialagents, including antivirals antibiotics, antifungals andantiparasitics. Specific antimicrobial agents that can be used with thefatty acid-derived, pre-cured biomaterials of the invention includePenicillin G, ephalothin, Ampicillin, Amoxicillin, Augmentin, Aztreonam,Imipenem, Streptomycin, Gentamicin, Vancomycin, Clindamycin,Erythromycin, Azithromycin, Polymyxin, Bacitracin, Amphotericin,Nystatin, Rifampicin, Tetracycline, Doxycycline, Chloramphenicol,Nalidixic acid, Ciprofloxacin, Sulfanilamide, Gantrisin, TrimethoprimIsoniazid (INH), para-aminosalicylic acid (PAS), and Gentamicin.

Therapeutically Effective Amounts and Dosage Levels

A therapeutically effective amount refers to that amount of a compoundsufficient to result in amelioration of symptoms, e.g., treatment,healing, prevention or amelioration of the relevant medical condition,or an increase in rate of treatment, healing, prevention or ameliorationof such conditions. When applied to an individual active ingredient,administered alone, a therapeutically effective amount refers to thatingredient alone. When applied to a combination, a therapeuticallyeffective amount can refer to combined amounts of the active ingredientsthat result in the therapeutic effect, whether administered incombination, serially or simultaneously. In various embodiments, whereformulations comprise two or more therapeutic agents, such formulationscan be described as a therapeutically effective amount of compound A forindication A and a therapeutically effective amount of compound B forindication B, such descriptions refer to amounts of A that have atherapeutic effect for indication A, but not necessarily indication B,and amounts of B that have a therapeutic effect for indication B, butnot necessarily indication A.

Actual dosage levels of the active ingredients in a fatty-acid based,pre-cure-derived biomaterial (e.g., coating and stand-alone film) of thepresent invention may be varied so as to obtain an amount of the activeingredients which is effective to achieve the desired therapeuticresponse without being unacceptably toxic. The selected dosage levelwill depend upon a variety of pharmacokinetic factors including theactivity of the particular therapeutic agent (drug) employed, or theester, salt or amide thereof, the mechanism of drug action, the time ofadministration, the drug release profile of the coating, the rate ofexcretion of the particular compounds being employed, the duration ofthe treatment, other drugs, compounds and/or materials used incombination with the particular compounds employed, and like factorsknown in the medical arts. For example, the invention provides afatty-acid based, pre-cure-derived biomaterial comprising a partiallycross-linked fatty acid and a therapeutic agent, wherein the therapeuticagent comprises at least 30%, e.g., at least 40%, e.g., at least 50%,e.g., at least 60%, e.g., at least 70%, by weight, of the biomaterialcomposition. In addition to the therapeutic agent, the biomaterial caninclude vitamin E in addition to the therapeutic agent.

Other Agents

The pre-cure-derived biomaterials (e.g., coatings and stand-alone films)of the present invention may also comprise one or more other chemicalsand entities in addition to the therapeutic agent, including, but notlimited to, one or more of: a pharmaceutically acceptable carrier, anexcipient, a surfactant, a binding agent, an adjuvant agent, and/or astabilizing agent (including preservatives, buffers and antioxidants).The other agents can perform one or more functions, such as, e.g., anadjuvant may also serve as a stabilizing agent.

In various embodiments, the coatings and stand-alone films of thepresent invention include one or more of a free radical scavenger anduptake enhancer. In various embodiments, the coatings and stand-alonefilms comprise vitamin E.

It should be noted that as utilized herein to describe the presentinvention, the term vitamin E and the term alpha-tocopherol, areintended to refer to the same or substantially similar substance, suchthat they are interchangeable and the use of one includes an implicitreference to both. Further included in association with the term vitaminE are such variations including but not limited to one or more ofalpha-tocopherol, beta-tocopherol, delta-tocopherol, gamma-tocopherol,alpha-tocotrienol, beta-tocotrienol, delta-tocotrienol,gamma-tocotrienol, alpha-tocopherol acetate, beta-tocopherol acetate,gamma-tocopherol acetate, delta-tocopherol acetate, alpha-tocotrienolacetate, beta-tocotrienol acetate, delta-tocotrienol acetate,gamma-tocotrienol acetate, alpha-tocopherol succinate, beta-tocopherolsuccinate, gamma-tocopherol succinate, delta-tocopherol succinate,alpha-tocotrienol succinate, beta-tocotrienol succinate,delta-tocotrienol succinate, gamma-tocotrienol succinate, mixedtocopherols, vitamin E TPGS, derivatives, analogs and pharmaceuticallyacceptable salts thereof.

Compounds that move too rapidly through a tissue may not be effective inproviding a sufficiently concentrated dose in a region of interest.Conversely, compounds that do not migrate in a tissue may never reachthe region of interest. Cellular uptake enhancers such as fatty acidsand cellular uptake inhibitors such as alpha-tocopherol can be usedalone or in combination to provide an effective transport of a givencompound to a given region or location. Both fatty acids andalpha-tocopherol can be included in the fatty acid-derived, pre-curedbiomaterials (e.g., coatings and stand-alone films) of the presentinvention described herein. Accordingly, fatty acids andalpha-tocopherol can be combined in differing amounts and ratios tocontribute to an fatty acid-derived, pre-cured biomaterial (e.g.,coating and stand-alone film) in a manner that provides control over thecellular uptake characteristics of the coating and any therapeuticagents mixed therein.

For example, the amount of alpha-tocopherol can be varied in thecoating. Alpha-tocopherol is known to slow autoxidation in fish oil byreducing hydroperoxide formation, which results in a decrease in theamount of cross-linking in a cured fatty acid-derived, pre-curedbiomaterial. In addition, alpha-tocopherol can be used to increasesolubility of drugs in the oil forming the coating. In variousembodiments, alpha-tocopherol can actually protect the therapeutic drugduring curing, which increases the resulting drug load in the coatingafter curing. Furthermore, with certain therapeutic drugs, the increaseof alpha-tocopherol in the coating can serve to slow and extend drugrelease due to the increased solubility of the drug in thealpha-tocopherol component of the coating. This reflects the cellularuptake inhibitor functionality of alpha-tocopherol, in that the uptakeof the drug is slowed and extended over time.

Curing and the Formation of Pre-Cures and Fatty-Acid-Based, Pre-CureDerived Biomaterials

Several methods are available to cure the oil starting material to formthe pre-cure, and then to cure the pre-cure (optionally containing oneor more therapeutic agents) to produce a fatty-acid-based,pre-cure-derived biomaterial for a drug release and delivery coating orstand-alone film in accordance with the present invention (for example,as described in US Patent Application Publications 2008/0118550,2007/0202149, 2007/0071798, 2006/0110457, 2006/0078586, 2006/0067983,2006/0067976, 2006/0067975). Preferred methods for curing the startingmaterial to produce a pre-cure, and then a fatty-acid-based,pre-cure-derived biomaterial include, but are not limited to, heating(e.g., employing an oven, a broadband infrared (IR) light source, acoherent IR light source (e.g., laser), and combinations thereof) andultraviolet (UV) irradiation. The starting material may be cross-linkedthrough auto-oxidation (i.e., oxidative cross-linking).

In accordance with various embodiments described herein, the drugrelease coatings of the present invention are formed of apre-cure-derived biomaterial, which can be derived from saturated andunsaturated fatty acid compounds (e.g., free fatty acids, fatty acidester, monoglycerides, diglycerides, triglycerides, metal salts, etc.).Preferably, the source of fatty acids described herein is saturated andunsaturated fatty acids such as those readily available in triglycerideform in various oils (e.g., fish oils). One method of the formation of apre-cure-derived biomaterial is accomplished through autoxidation of theoil. As a liquid oil containing unsaturated fatty acid is heated,autoxidation occurs with the absorption of oxygen into the oil to createhydroperoxides in an amount dependent upon the amount of unsaturated(C═C) sites in the oil. However, the (C═C) bonds are not consumed inthis initial reaction. Concurrent with the formation of hydroperoxidesis the isomerization of (C═C) double bonds from cis to trans in additionto double bond conjugation. Continued heating of the oil results in thesolidifying of the coating through the formation of cross-linking and bythe further reaction of the hydroperoxides and the cleavage of C═Cdouble bonds, which convert them into lower molecular weight secondaryoxidation byproducts including aldehydes, ketones, alcohols, fattyacids, esters, lactones, ethers, and hydrocarbons which can eitherremain within the coating and/or are volatilized during the process.

The type and amount of cross-links formed during oil oxidation can betailored depending on the conditions selected (e.g., coating thickness,temperature, metal composition, etc.). For instance, heating of the oilallows for cross-linking between the fish oil unsaturated chains using acombination of peroxide (C—O—C), ether (C—O—C), and hydrocarbon (C—C)bridges (see, e.g., F. D. Gunstone, “Fatty Acid and Lipid Chemistry.”1999). However, heating at lower temperatures (i.e., below 150° C.)results in the formation of predominantly peroxide cross-links whereheating at higher temperatures (i.e., above 150° C.) results in thethermal degradation of peroxides and C═C and ether cross-links dominate(F. D. Gunstone, 1999). Schematic illustrations of various cross-linkingmechanisms and schemes are shown in FIGS. 1-2.

In addition to thermal curing processes, oxidation of oils can also beinduced by light (e.g., photo-oxygenation). Photo-oxygenation is limitedto C═C carbon atoms and results in a conversion from cis to trans C═Cisomers during curing (as occurs with heat initiated curing). However,photo-oxygenation using UV is a relatively quicker reaction thanautoxidation from heat curing, in the realm of about 1000-1500 timesfaster. The quicker reaction especially holds true for methyleneinterrupted polyunsaturated fatty acids, such as EPA and DHA, which arefound in the fish oil based embodiments of the present invention.

An important aspect of UV curing when compared to heat curing is thatalthough the byproducts obtained by both curing methods are similar,they are not necessarily identical in amount or chemical structure. Onereason for this is due to the ability of photo-oxygenation to createhydroperoxides at more possible C═C sites.

Photo-oxygenation, such as that which results from UV curing, due to itsenhanced ability to create inner hydroperoxides, also results in theability to form relatively greater amounts of cyclic byproducts, whichalso relates to peroxide cross-linking between fish oil hydrocarbonchains. For example, photo-oxygenation of linolenate results in 6different types of hydroperoxides to be formed, whereas autoxidationresults in only 4. The greater amount of hydroperoxides created usingphoto-oxygenation results in a similar, but slightly different,structure and amount of secondary byproducts to be formed relative toautoxidation from heat curing. Specifically, these byproducts arealdehydes, ketones, alcohols, fatty acids, esters, lactones, ethers, andhydrocarbons.

Depending on the oil curing conditions and the fatty acid composition ofthe starting oil, a fatty acid-derived biomaterial (i.e., pre-cure andpre-cure derived) can be produced by curing the oil so as to oxidize thedouble bonds of the unsaturated fatty acid chains while predominantlypreserving triglyceride ester functional groups. The oxidation of theunsaturated fatty acid chains results in the formation ofhydroperoxides, which, with continued curing, are converted intoaldehydes, ketones, alcohols, fatty acids, esters, lactones, ethers, andhydrocarbons. With continued heating of the oxidized oil, the byproductsare volatilized, resulting in an increase in the coating viscosity inaddition to the formation of ester cross-links. The formation of esterand lactone cross-links can occur different types of mechanisms (i.e.,esterification, alcoholysis, acidolysis, interesterification asdescribed in F. D. Gunstone, 1999) between the hydroxyl and carboxylfunctional components in the coating formed from the oxidation process(i.e., glyceride and fatty acid). The cross-linking reaction can formdifferent types of ester linkages such as ester, anhydride, aliphaticperoxide, and lactones. FIGS. 3-4 summarize the mechanism for theformation of the oil derived biomaterial and reaction chemistry,respectively. As described in FIG. 3, after oxidation of the oil, i.e.,after forming the precure, a therapeutic agent can optionally be added.Vitamin E can also be added in addition to the therapeutic agent, whichwill protect the agent and pre-cured oil from further oxidation, butdoes not inhibit further cross linking of the fatty acid and/orglyceride components of the oil. FIG. 5 provides a schematic ofdifferent methods to form esters from oils reaction schemes forillustrative purposes, but is not meant to be limiting in its scope tothe invention.

Pre-cure-derived biomaterial coatings and stand-alone films of thepresent invention can be formed from an oil component. The term “oilcomponent” is also referred to herein as the “oil-containing startingmaterial.” The “oil-containing starting material” may be natural orderived from synthetic sources. Preferably, the “oil containing startingmaterial” comprises unsaturated fatty acids. The oil component can beeither an oil, or an oil composition. The oil component can be anaturally occurring oil, such as fish oil, flax seed oil, grape seedoil, a synthetic oil, or other oils having desired characteristics. Oneexample embodiment of the present invention makes use of a fish oil inpart because of the high content of omega-3 fatty acids, which canprovide healing support for damaged tissue, as discussed herein. Thefish oil can also serve as an anti-adhesion agent. In addition, the fishoil maintains anti-inflammatory or non-inflammatory properties as well.The present invention is not limited to formation of the fattyacid-derived, pre-cured biomaterial with fish oil as the naturallyoccurring oil. However, the following description makes reference to theuse of fish oil as one example embodiment. Other naturally occurringoils or synthetic oils can be utilized in accordance with the presentinvention as described herein.

Coating Hydrolysis and Bioabsorption Chemistry of Fatty-Acid-Based,Pre-Cure Derived Biomaterials

Biodegradable and bioabsorbable implantable materials with ester,lactone, and anhydride functional groups are typically broken down byeither chemical and/or enzymatic hydrolysis mechanisms (K. Park et al.,“Biodegradable Hydrogels for Drug Delivery.” 1993; J. M. Andersen,“Perspectives on the In-Vivo Responses of Biodegradable Polymers.” inBiomedical Applications of Synthetic Biodegradable Polymers, edited byJeffrey O. Hollinger, 1995, pgs 223-233). Chemical hydrolysis of apre-cure-derived biomaterial occurs when the functional group present inthe material is cleaved by water. An example of chemical hydrolysis of atriglyceride under basic conditions is presented in FIG. 6. Enzymatichydrolysis is the cleavage of functional groups in a pre-cure-derivedbiomaterial caused by the reaction with a specific enzyme (i.e.,triglycerides are broken down by lipases (enzymes) that result in freefatty acids that can then be transported across cell membranes). Thelength of time a biodegradable and/or biodegradable pre-cure-derivedbiomaterial takes to be hydrolyzed is dependent on several factors suchas the cross-linking density of the material, the thickness, thehydration ability of the coating, the crystallinity of thepre-cure-derived biomaterial, and the ability for the hydrolysisproducts to be metabolized by the body (K. Park et al., 1993 and J. M.Andersen, 1995).

A bio-absorbable substance is different from a biodegradable substance.Biodegradable is generally defined as capable of being decomposed bybiological agents, or capable of being broken down by microorganisms orbiological processes. Biodegradable substances can cause an inflammatoryresponse due to either the parent substance or those formed duringbreakdown, and they may or may not be absorbed by tissues. Somebiodegradable substances are limited to bulk erosion mechanism forbreakdown. For example, a commonly used biodegradable polymer, PLGA(poly(lactic-co-glycolic acid)) undergoes chemical hydrolysis in-vivo toform two alpha-hydroxy acids, specifically glycolic and lactic acids.Although glycolic and lactic acids are byproducts of various metabolicpathways in the body, it has been previously demonstrated in previousmedical implant and local drug delivery applications that a localconcentration of these products results in an acidic environment to beproduced, which can lead to inflammation and damage to local tissue (S.Dumitriu, “Polymeric Biomaterials.” 2002). Clinically, this can lead toimpaired clinical outcomes such as restenosis (D. E. Drachman and D. I.Simon. Current Atherosclerosis Reports. 2005, Vol 7, pgs 44-49; S. E.Goldblum et al. Infection and Immunity. 1989, Vol. 57, No. 4, pgs1218-1226) and impaired healing in a coronary stent application whichcan lead to late-stent thrombosis or adhesion formation in an abdominalhernia repair (Y. C. Cheong et al. Human Reproduction Update. 2001; Vol.7, No. 6: pgs 556-566). Thus, an ideal pre-cure-derived biomaterialshould not only demonstrate excellent biocompatibility uponimplantation, but should also maintain that biocompatibility during thelife of its implantation with its hydrolysis byproducts being absorbableby local tissue.

The bio-absorbable nature of the pre-cure-derived biomaterials used as astand-alone film, a coating for a medical device, or in drug deliveryapplications results in the biomaterial being absorbed over time by thecells of the body tissue. In various embodiments, there aresubstantially no substances in the coating, or in vivo conversionby-products of the coating, that induce an inflammatory response, e.g.,the coating converts in vivo into non-inflammatory components. Forexample, in various embodiments, the coatings of the present inventionupon absorption and hydrolysis do not produce lactic acid and glycolicacid break-down products in measurable amounts. The chemistry of thepre-cure-derived biomaterial described herein consists of predominantlyfatty acid and glyceride components that can either be hydrolyzedin-vivo by chemical and/or enzymatic means which results in the releaseof fatty acid and glyceride components that can be transported acrosscell membranes. Subsequently, the fatty acid and glyceride componentseluted from the pre-cure-derived biomaterial are directly metabolized bycells (i.e., they are bio-absorbable). The bio-absorbable nature of thecoating and stand-alone film of the present invention results in thecoating being absorbed over time, leaving only an underlying delivery orother medical device structure that is biocompatible. There issubstantially no foreign body inflammatory response to thebio-absorbable coating or its hydrolysis breakdown products in thepreferred embodiments of the present invention.

Fatty-Acid-Based, Pre-Cure Derived Biomaterial Biocompatibility andIn-Vivo Performance

The process of making the pre-cure-derived biomaterials (e.g., coatingor stand-alone film) as described herein led to some unexpected chemicalprocesses and characteristics in view of traditional scientific reportsin the literature about the oxidation of oils (J. Dubois et al. JAOCS.1996, Vol. 73, No. 6., pgs 787-794. H. Ohkawa et al., AnalyticalBiochemistry, 1979, Vol. 95, pgs 351-358; H. H. Draper, 2000, Vol. 29,No. 11, pgs 1071-1077). Oil oxidation has traditionally been of concernfor oil curing procedures due to the formation of reactive byproductssuch as hydroperoxides and alpha-beta unsaturated aldehydes that are notconsidered to be biocompatible (H. C. Yeo et al. Methods in Enzymology.1999, Vol. 300, pgs 70-78; S-S. Kim et al. Lipids. 1999, Vol. 34, No. 5,pgs 489-496). However, the oxidation of fatty acids from oils and fatsare normal and important in the control of biochemical processesin-vivo. For example, the regulation of certain biochemical pathways,such as to promote or reduce inflammation, is controlled by differentlipid oxidation products (V. N. Bochkov and N. Leitinger. J. Mol. Med.2003; Vol. 81, pgs 613-626). Additionally, omega-3 fatty acids are knownto be important for human health and specifically EPA and DHA are knownto have anti-inflammatory properties in-vivo. However, EPA and DHA arenot anti-inflammatory themselves, but it is the oxidative byproductsthey are biochemically converted into that produce anti-inflammatoryeffects in-vivo (V. N. Bochkov and N. Leitinger, 2003; L. J. Roberts IIet al. The Journal of Biological Chemistry. 1998; Vol. 273, No. 22, pgs13605-13612). Thus, although there are certain oil oxidation productsthat are not biocompatible, there are also several others that havepositive biochemical properties in-vivo (V. N. Bochkov and N. Leitinger,2003; F. M. Sacks and H. Campos. J Clin Endocrinol Metab. 2006; Vol. 91,No. 2, pgs 398-400; A. Mishra et al. Arterioscler Thromb Vasc Biol.2004; pgs 1621-1627). Thus, by selecting the appropriate processconditions, a fatty acid-derived cross-linked hydrophobic fattyacid-derived, pre-cured biomaterial (from, e.g., fish oil) can becreated and controlled using oil oxidation chemistry with a finalchemical profile that will have a favorable biological performancein-vivo.

The process of making a pre-cure-derived biomaterial as described hereinleads to a final chemical profile that is biocompatible, minimizesadhesion formation, acts as a tissue separating barrier, and isnon-inflammatory with respect to the material chemistry and the productsproduced upon hydrolysis and absorption by the body in-vivo. The reasonfor these properties is due to several unique characteristics of thefatty acid-derived, pre-cured biomaterials (e.g., coatings orstand-alone films) of the invention.

One important aspect of the invention is that no toxic, short-chainedcross-linking agents (such as glutaraldehyde) are used to form the fattyacid-derived, pre-cured biomaterials (e.g., coatings or stand-alonefilms) of the invention. It has been previously demonstrated in theliterature that short chain cross-linking agents can elute duringhydrolysis of biodegradable polymers and cause local tissueinflammation. The process of creating pre-cure-derived biomaterials doesnot involve cross-linking agents because the oil is solely cured into acoating using oil autoxidation or photo-oxidation chemistry. Theoxidation process results in the formation of carboxyl and hydroxylfunctional groups that allow for the pre-cure-derived biomaterial tobecome hydrated very rapidly and become slippery, which allows forfrictional injury during and after implantation to be significantlyreduced and/or eliminated. The methods of making the pre-cure-derivedbiomaterials described herein allow the alkyl chains of the fatty acid,glyceride and other lipid byproducts present in the coating to bedisordered, which creates a coating that is flexible and aids inhandling of the material while being implanted.

There are several individual chemical components of the coating that aidin its biocompatibility and its low to non-inflammatory responseobserved in-vivo. One critical aspect is that the process of creating apre-cure-derived biomaterial as described herein results in low tonon-detectable amounts of oxidized lipid byproducts of biocompatibilityconcern, such as aldehydes. These products are either almost completelyreacted or volatilized during the curing process as described herein.The process of creating a pre-cure-derived biomaterial largely preservesthe esters of the native oil triglycerides and forms ester and/orlactone cross-links, which are biocompatible (K. Park et al., 1993; J.M. Andersen, 1995).

In addition to general chemical properties of a pre-cure-derivedbiomaterial that assists in its biocompatibility, there are alsospecific chemical components that have positive biological properties.Another aspect is that the fatty acid chemistry produced upon creationof a pre-cure-derived biomaterial is similar to the fatty acid chemistryof tissue, as presented in FIG. 7. Thus, as fatty acids are eluting fromthe coating they are not viewed as being “foreign” by the body and causean inflammatory response. In fact, C14 (myristic) and C16 (palmitic)fatty acids present in the coating have been shown in the literature toreduce production of α-TNF, an inflammatory cytokine. The expression ofα-TNF has been identified as one of the key cytokines responsible for“turning on” inflammation in the peoritoneal after hernia repair, whichcan then lead to abnormal healing and adhesion formation (Y. C. Cheonget al., 2001). α-TNF is also an important cytokine in vascular injuryand inflammation (D. E. Drachman and D. I. Simon, 2005; S. E. Goldblum,1989), such as vascular injury caused during a stent deployment. Inaddition to the fatty acids just specified, there have also beenadditional oxidized fatty acids identified that have anti-inflammatoryproperties. A final component identified from the fatty acid-derivedcoatings as described herein are delta-lactones (i.e., 6-membered ringcyclic esters). Delta-lactones have been identified as having anti-tumorproperties (H. Tanaka et al. Life Sciences 2007; Vol. 80, pgs1851-1855).

These components identified are not meant to be limiting in scope to thepresent invention as changes in starting oil composition and/or processconditions can invariably alter the fatty acid and/or oxidativebyproduct profiles and can be tailored as needed depending on theintended purpose and site of application of the fatty acid-derived,pre-cured biomaterial.

In summary, the biocompatibility and observed in in-vivo performance ofpre-cure-derived biomaterials described herein is due to the elution offatty acids during hydrolysis of the material during implantation andhealing and is not only beneficial as to prevent a foreign body responsein-vivo due to the similarity of the fatty acid composition of thematerial to native tissue (i.e., a biological “stealth” coating), butthe specific fatty acids and/or other lipid oxidation components elutingfrom the coating aid in preventing foreign body reactions and reducingor eliminating inflammation, which leads to improved patient outcomes.Additionally, the fatty acid and glyceride components eluted from thepre-cure-derived biomaterial are able to be absorbed by local tissue andmetabolized by cells, in, for example, the Citric Acid Cycle (M. J.Campell, “Biochemistry: Second Edition.” 1995, pgs 366-389). Hence, thepre-cure-derived biomaterial (e.g., coating or stand-alone film)described herein is also bioabsorbable.

Accordingly, in one aspect, the invention provides a bio-absorbable,oil-based coating for a medical device, comprising a cross-linked fattyacid oil-derived biomaterial with a pre-cured component and atherapeutic agent. The invention also provides a bio-absorbable,oil-based stand-alone film, comprising a cross-linked fatty acidoil-derived biomaterial with a pre-cured component and a therapeuticagent. The coating and stand-alone film can be prepared according to themethods discussed herein.

Methods of Treatment Using Fatty Acid-Derived Materials

Also provided herein is a fatty acid-based, pre-cure-derived biomaterialsuitable for treating or preventing disorders related to vascular injuryand/or vascular inflammation. The fatty acid-based, pre-cure-derivedbiomaterial can also be used to treat or prevent injury to tissue, e.g.,soft tissue. The fatty acid-based, pre-cure-derived biomaterial can be acoating for a medical device or a stand-alone film. In anotherembodiment, the source of the fatty acid for the biomaterial is an oil,such as fish oil.

In general, four types of soft tissue are present in humans: epithelialtissue, e.g., the skin and the lining of the vessels and many organs;connective tissue, e.g., tendons, ligaments, cartilage, fat, bloodvessels, and bone; muscle, e.g., skeletal (striated), cardiac, orsmooth; and nervous tissue, e.g., brain, spinal cord and nerves. Thefatty acid-based, pre-cure-derived biomaterial of the invention (e.g.,pre-cure-derived stand-alone film) can be used to treat injury to thesesoft tissue areas. Thus, in one embodiment, the fatty acid-based,pre-cure-derived biomaterial of the invention (e.g., pre-curedstand-alone film) can be used for promotion of proliferation of softtissue for wound healing. Furthermore, following acute trauma, softtissue can undergo changes and adaptations as a result of healing andthe rehabilitative process. Such changes include, but are not limitedto, metaplasia, which is conversion of one kind of tissue into a formthat is not normal for that tissue; dysplasia, with is the abnormaldevelopment of tissue; hyperplasia, which is excessive proliferation ofnormal cells in the normal tissue arrangement; and atrophy, which is adecrease in the size of tissue due to cell death and resorption ordecreased cell proliferation. Accordingly, the fatty acid-based,pre-cure-derived biomaterial of the invention (e.g., pre-curedstand-alone film) can be used for the diminishment or alleviation of atleast one symptom associated with or caused by acute trauma in softtissue.

In one embodiment of the present invention, as described below, thefatty acid-based, pre-cure-derived biomaterial can be used, for example,to prevent tissue adhesion. The tissue adhesion can be, for example, aresult of blunt dissection. Blunt dissection can be generally describedas dissection accomplished by separating tissues along natural cleavagelines without cutting. Blunt dissection is executed using a number ofdifferent blunt surgical tools, as is understood by those of ordinaryskill in the art. Blunt dissection is often performed in cardiovascular,colo-rectal, urology, gynecology, upper GI, and plastic surgeryapplications, among others.

After the blunt dissection separates the desired tissues into separateareas, there is often a need to maintain the separation of thosetissues. In fact, post surgical adhesions can occur following almost anytype of surgery, resulting in serious postoperative complications. Theformation of surgical adhesions is a complex inflammatory process inwhich tissues that normally remain separated in the body come intophysical contact with one another and attach to each other as a resultof surgical trauma.

It is believed that adhesions are formed when bleeding and leakage ofplasma proteins from damaged tissue deposit in the abdominal cavity andform what is called a fibrinous exudate. Fibrin, which restores injuredtissues, is sticky, so the fibrinous exudate may attach to adjacentanatomical structures in the abdomen. Post-traumatic or continuousinflammation exaggerates this process, as fibrin deposition is a uniformhost response to local inflammation. This attachment seems to bereversible during the first few days after injury because the fibrinousexudates go through enzymatic degradation caused by the release offibrinolytic factors, most notably tissue-type plasminogen activator(t-PA). There is constant play between t-PA and plasminogen-activatorinhibitors. Surgical trauma usually decreases t-PA activity andincreases plasminogen-activator inhibitors. When this happens, thefibrin in the fibrinous exudate is replaced by collagen. Blood vesselsbegin to form, which leads to the development of an adhesion. Once thishas occurred, the adhesion is believed to be irreversible. Therefore,the balance between fibrin deposition and degradation during the firstfew days post-trauma is critical to the development of adhesions(Holmdahl L. Lancet 1999; 353: 1456-57). If normal fibrinolytic activitycan be maintained or quickly restored, fibrous deposits are lysed andpermanent adhesions can be avoided. Adhesions can appear as thin sheetsof tissue or as thick fibrous bands.

Often, the inflammatory response is also triggered by a foreignsubstance in vivo, such as an implanted medical device. The body seesthis implant as a foreign substance, and the inflammatory response is acellular reaction to wall off the foreign material. This inflammationcan lead to adhesion formation to the implanted device; therefore amaterial that causes little to no inflammatory response is desired.

Thus, the fatty acid-based, pre-cure-derived biomaterial (e.g.,stand-alone film) of the present invention may be used as a barrier tokeep tissues separated to avoid the formation of adhesions, e.g.,surgical adhesions. Application examples for adhesion prevention includeabdominal surgeries, spinal repair, orthopedic surgeries, tendon andligament repairs, gynecological and pelvic surgeries, and nerve repairapplications. The fatty acid-based, pre-cure-derived biomaterial (e.g.,stand-alone film) may be applied over the trauma site or wrapped aroundthe tissue or organ to limit adhesion formation. The addition oftherapeutic agents to the fatty acid-based, pre-cure-derived biomaterialused in these adhesion prevention applications can be utilized foradditional beneficial effects, such as pain relief or infectionminimization. Other surgical applications of the fatty acid-based,pre-cure-derived biomaterial may include using a stand-alone film as adura patch, buttressing material, internal wound care (such as a graftanastomotic site), and internal drug delivery system. The fattyacid-based, pre-cure-derived biomaterial may also be used inapplications in transdermal, wound healing, and non-surgical fields. Thefatty acid-based, pre-cure-derived biomaterial may be used in externalwound care, such as a treatment for burns or skin ulcers. The fattyacid-based, pre-cure-derived biomaterial may be used without anytherapeutic agent as a clean, non-permeable, non-adhesive,non-inflammatory, anti-inflammatory dressing, or the fatty acid-based,pre-cure-derived biomaterial may be used with one or more therapeuticagents for additional beneficial effects. The fatty acid-based,pre-cure-derived biomaterial may also be used as a transdermal drugdelivery patch when the fatty acid-based, pre-cure-derived biomaterialis loaded or coated with one or more therapeutic agents.

The process of wound healing involves tissue repair in response toinjury and it encompasses many different biologic processes, includingepithelial growth and differentiation, fibrous tissue production andfunction, angiogenesis, and inflammation. Accordingly, the fattyacid-based, pre-cure-derived biomaterial (e.g., stand-alone film)provides an excellent material suitable for wound healing applications.

Modulated Healing

Also provided herein is a fatty acid-based, pre-cure-derived biomaterialsuitable for achieving modulated healing in a tissue region in needthereof, wherein the composition is administered in an amount sufficientto achieve said modulated healing. In one embodiment, the fattyacid-based, pre-cure-derived biomaterial is a medical coating for amedical device or a stand-alone film. In another embodiment, the sourceof the fatty acid for the biomaterial is an oil, such as fish oil.

Modulated healing can be described as the in-vivo effect observedpost-implant in which the biological response is altered resulting in asignificant reduction in foreign body response. As utilized herein, thephrase “modulated healing” and variants of this language generallyrefers to the modulation (e.g., alteration, delay, retardation,reduction, detaining) of a process involving different cascades orsequences of naturally occurring tissue repair in response to localizedtissue injury, substantially reducing their inflammatory effect.Modulated healing encompasses many different biologic processes,including epithelial growth, fibrin deposition, platelet activation andattachment, inhibition, proliferation and/or differentiation, connectivefibrous tissue production and function, angiogenesis, and several stagesof acute and/or chronic inflammation, and their interplay with eachother. For example, the fatty acids described herein can alter, delay,retard, reduce, and/or detain one or more of the phases associated withhealing of vascular injury caused by medical procedures, including, butnot limited to, the inflammatory phase (e.g., platelet or fibrindeposition), and the proliferative phase. In one embodiment, “modulatedhealing” refers to the ability of a fatty acid derived biomaterial toalter a substantial inflammatory phase (e.g., platelet or fibrindeposition) at the beginning of the tissue healing process. As usedherein, the phrase “alter a substantial inflammatory phase” refers tothe ability of the fatty acid derived biomaterial to substantiallyreduce the inflammatory response at an injury site. In such an instance,a minor amount of inflammation may ensue in response to tissue injury,but this level of inflammation response, e.g., platelet and/or fibrindeposition, is substantially reduced when compared to inflammation thattakes place in the absence of the fatty acid derived biomaterial.

For example, the fatty acid-based, pre-cure-derived biomaterial (e.g.,fatty acid-based, pre-cure-derived coating or fatty acid-based,pre-cure-derived stand-alone film) of the present invention has beenshown experimentally in animal models to delay or alter the inflammatoryresponse associated with vascular injury, as well as excessive formationof connective fibrous tissue following tissue injury. The fattyacid-based, pre-cure-derived biomaterial (e.g., coating or stand-alonefilm) of the present invention can delay or reduce fibrin deposition andplatelet attachment to a blood contact surface following vascularinjury.

Accordingly, the fatty acid-based, pre-cure-derived biomaterial (e.g.,coating or stand-alone film) of the present invention provides anexcellent absorbable cellular interface suitable for use with a surgicalinstrument or medical device that results in a modulated healing effect,avoiding the generation of scar tissue and promoting the formation ofhealthy tissue at a modulated or delayed period in time following theinjury. Without being bound by theory, this modulated healing effect canbe attributed to the modulation (e.g., alteration, delay, retardation,reduction, detaining) of any of the molecular processes associated withthe healing processes of vascular injury. For example, the fattyacid-based, pre-cure-derived biomaterial (e.g., fatty acid-based,pre-cure-derived coating or fatty acid-based, pre-cure-derived film) ofthe present invention can act as a barrier or blocking layer between amedical device implant (e.g., a surgical mesh, graft, or stent), orsurgical instrument, and the cells and proteins that compose the vesselwall, such as the endothelial cells and smooth muscle cells that linethe vessel's interior surface. The barrier layer prevents theinteraction between the surgical implant and the vessel surface, therebypreventing the initiation of the healing process by the cells andproteins of the vessel wall. In this respect, the barrier layer acts asa patch that binds to the vessel wall and blocks cells and proteins ofthe vessel wall from recognizing the surgical implant (i.e., the barrierlayer blocks cell-device and/or protein-device interactions), therebyblocking the initiation of the vascular healing process, and avoidingthe fibrin activation and deposition and platelet activation anddeposition.

In another non-binding example, the modulated healing effect can beattributed to the modulation (e.g., alteration, delay, retardation,reduction, detaining) of signaling between the cells and proteins thatcompose the vessel wall and various components of the bloodstream thatwould otherwise initiate the vascular healing process. Stateddifferently, at the site of vascular injury, the fatty acid derivedbiomaterial (e.g., coating or stand-alone film) of the present inventioncan modulate the interaction of cells of the vessel wall, such asendothelial cells and/or smooth muscle cells, with other cells and/orproteins of the blood that would otherwise interact with the damagedcells to initiate the healing process. Additionally, at the site ofvascular injury, the fatty acid-based, pre-cure-derived biomaterial(e.g., coating or stand-alone film) of the present invention canmodulate the interaction of proteins of the vessel wall with other cellsand/or proteins of the blood, thereby modulating the healing process.

The fatty acid-based, pre-cure-derived biomaterial (e.g., coating orstand-alone film) of the present invention can be designed to maintainits integrity for a desired period of time, and then begin to hydrolyzeand be absorbed into the tissue that it is surrounded by. Alternatively,the fatty acid-based, pre-cure-derived biomaterial can be designed suchthat, to some degree, it is absorbed into surrounding tissue immediatelyafter the fatty acid derived biomaterial is inserted in the subject.Depending on the formulation of the fatty acid-based, pre-cure-derivedbiomaterial, it can be completely absorbed into surrounding tissuewithin a time period of 1 day to 24 months, e.g., 1 week to 12 months,e.g., 1 month to 10 months, e.g., 3 months to 6 months. Animal studieshave shown resorption of the fatty acid derived biomaterial occurringupon implantation and continuing over a 3 to 6 month period, and beyond.

Tailoring of Drug Release Profiles

In various aspects, the present invention provides methods of curing aof a fatty acid-derived coating, preferably fish oil, to provide a fattyacid-derived, pre-cured biomaterial coating or stand-alone filmcontaining one or more therapeutic agents that can tailor the releaseprofile of a therapeutic agent from the coating or film. The releaseprofile can be tailored, e.g., through changes in oil (e.g., fish oil)chemistry by varying coating composition, temperature, and cure times.The position of the drug-containing layer on the coated device providesan additional mechanism to alter the release profile of thenon-polymeric cross-linked fatty acid-derived, pre-cured biomaterialcoating. This can be achieved, e.g., by loading a drug into a cured basecoating layer and coating a topcoat overlayer cured coating onto thepreviously cured encapsulating base layer.

An advantage of the cured fish oil coating and stand-alone film invarious embodiments of the present invention is that the curingconditions utilized (i.e., cure time and temperature) can directlyinfluence the amount of coating cross-linking density and byproductformation, which in turn effects the coating degradation. Thus, byaltering the curing conditions employed, the dissolution rate of atherapeutic compound of interest contained in the coating can also bealtered.

In various embodiments of the present invention, an agent, such as,e.g., a free radical scavenger, can be added to the starting material totailor the drug release profile of the fatty acid-derived, pre-curedbiomaterial that is formed. In various embodiments, vitamin E is addedto the starting material to, for example, to slow down autoxidation infish oil by reducing hydroperoxide formation, which can result in adecrease in the amount of cross-linking observed in a cured fish oilcoating. In addition, other agents can be used to increase thesolubility of a therapeutic agent in the oil component of the startingmaterial, protect the drug from degradation during the curing process,or both. For example, vitamin E can also be used to increase thesolubility of certain drugs in a fish oil starting material, and therebyfacilitate tailoring the drug load of the eventual cured coating. Thus,varying the amount of vitamin E present in the coating provides anadditional mechanism to alter the cross-linking and chemical compositionof the fatty acid-derived, pre-cured biomaterials (e.g., coatings andstand-alone films) of the present invention.

In various embodiments, the present invention provides coatings andstand-alone films where the drug release profile of the fattyacid-derived, pre-cured biomaterial is tailored through the provision oftwo or more coatings and selection of the location of the therapeuticagent. The drug location can be altered, e.g., by coating a bare portionof a medical device with a first starting material and creating a firstcured coating, then coating at least a portion of the firstcured-coating with the drug-oil formulation to create a second overlayercoating. The first starting material can contain one or more therapeuticagents. In various embodiments, the second overlayer coating is alsocured. The drug load, drug release profiles, or both, of the firstcoating, the overlay coating, or both, can be tailored through the useof different curing conditions and/or addition of free radicalscavengers (e.g., vitamin E), as described herein. The process ofproviding two layers can be extended to provide three or more layers,wherein at least one of the layers comprises a hydrophobic, cross-linkedfatty acid-derived, pre-cured biomaterial prepared from a fatty-acidcontaining oil, such as fish oil. In addition, one or more of the layerscan be drug eluting, and the drug release profile of such layers can betailored using the methods described herein.

In various embodiments, the present invention provides coatings wherethe drug release profile of the overall coating is tailored through theprovision of two or more coating regions with different drug releaseprofiles and selection of the location of the therapeutic agent. Invarious embodiments, the formation of different coating regions withdifferent drug release properties is obtained by location specificcuring conditions, e.g., location specific UV irradiation, and/orlocation specific deposition of a starting material on the coateddevice, e.g., by ink jet printing methods.

Coating Approaches

FIG. 8 illustrates one method of making a medical device of the presentinvention, such as, e.g., a drug eluting coated stent, in accordancewith one embodiment of the present invention. The process involvesproviding a medical device, such as the stent (step 100). A coating of astarting material, which is a non-polymeric cross-linked fattyacid-derived, pre-cured biomaterial coating, is then applied to themedical device (step 102). One of ordinary skill in the art willappreciate that this basic method of application of a coating to amedical device, such as a stent, can have a number of differentvariations falling within the process described. The step of applying acoating substance to form a coating on the medical device can include anumber of different application methods. For example, the medical devicecan be dipped into a liquid solution of the coating substance. Thecoating substance can be sprayed onto the device. Another applicationmethod is painting the coating substance on to the medical device. Oneof ordinary skill in the art will appreciate that other methods, such aselectrostatic adhesion, can be utilized to apply the coating substanceto the medical device. Some application methods may be particular to thecoating substance and/or to the structure of the medical devicereceiving the coating. Accordingly, the present invention is not limitedto the specific embodiments of starting material application describedherein, but is intended to apply generally to the application of thestarting material which is to become a fatty acid-derived, pre-curedbiomaterial coating of a medical device, taking whatever precautions arenecessary to make the resulting coating maintain desiredcharacteristics.

FIG. 9 is a flowchart illustrating one example implementation of themethod of FIG. 8. In accordance with the steps illustrated in FIG. 9, abio-absorbable carrier component (e.g., a fatty acid source, such as anaturally occurring oil) is provided (step 110). The carrier is thenpre-cured (“partially cured”) to induce an initial amount of crosslinking (step 112). The resulting material can then be combined with atherapeutic agent, to form a pre-cured material that is to become afatty acid-based, pre-cure-derived biomaterial coating (step 114). Thepre-cured material is applied to the medical device, such as the stent10, to form the coating (step 116). The coating is then cured (step 118)by any of the curing methods described herein to form a fattyacid-derived, pre-cured biomaterial coating.

In certain instances, a therapeutic agent that is desired forincorporation into a fatty acid-derived biomaterial coating is notstable to the thermal/UV curing process utilized to create the devicecoating (e.g., there is a significant amount of drug degradationobserved). In order to maintain therapeutic agent composition andminimize degradation of the therapeutic agent, the fatty acid startingmaterial (e.g., fish oil) can be first partially cured (“pre-cured”), inthe absence of the therapeutic agent, to oxidize the unsaturatedcomponents in the oil. Such a process increases the viscosity of the oiland reduces its reactivity by partially cross-linking the fatty acids ofthe oil, for, e.g., medical device coating applications. The therapeuticagent can then be combined with the pre-cure in an organic solvent andsprayed and/or cast onto a medical device and/or as a stand-alone filmmaterial, and subsequently heated to form a final cross-linked material(i.e., a fatty acid-based, pre-cure-derived coating) for use in itsintended application. This process results in incorporating thetherapeutic agent into the fatty acid-derived, pre-cured biomaterial forextended drug release from the coating. Alternatively, after thecreation of the pre-cure, an antioxidant such as Vitamin E can becombined with the therapeutic agent and an organic solvent forapplication onto a medical device or to create a stand-alone film. Thiscoating is then also final cured into a fatty acid-derived, pre-curedbiomaterial. While the antioxidant (e.g., Vitamin E) is oxidized duringthe final cure step, it prevents the therapeutic and oil components frombeing further oxidized and preserves the drug composition and activity.Although the antioxidant prevents further oxidation of the therapeuticand pre-cured oil components, it does not inhibit the formation of estercross-links between the fatty acids upon cure, because the reactivecarboxyl and hydroxyl functional groups needed to create the fattyacid-derived, pre-cured biomaterial were created during the initialthermal/UV curing treatment of the oil starting material, i.e., duringthe creation of the pre-cure.

The coated medical device is then sterilized using any number ofdifferent sterilization processes (step 118). For example, sterilizationcan be implemented utilizing ethylene oxide, gamma radiation, E beam,steam, gas plasma, or vaporized hydrogen peroxide. One of ordinary skillin the art will appreciate that other sterilization processes can alsobe applied, and that those listed herein are merely examples ofsterilization processes that result in a sterilization of the coatedstent, preferably without having a detrimental effect on the coating 20.

It should be noted that the fatty acid component (e.g., a fish oil) canbe added multiple times to create multiple tiers in forming the coating.For example, if a thicker coating is desired, additional tiers of thefatty acid component can be added after steps 100, 102, 110, 112, 114,116, 118 and/or 120. Different variations relating to when the fattyacid is cured and when other substances are added are possible in anumber of different process configurations. Accordingly, the presentinvention is not limited to the specific sequence illustrated. Rather,different combinations of the basic steps illustrated are anticipated bythe present invention.

FIGS. 10A-10E illustrate some of the other forms of medical devicesmentioned above in combination with the coating 10 of the presentinvention. FIG. 10A shows a graft 50 with the coating 10 coupled oradhered thereto. FIG. 10B shows a catheter balloon 52 with the coating10 coupled or adhered thereto. FIG. 10C shows a stent 54 with thecoating 10 coupled or adhered thereto. FIG. 10D illustrates a stent 10in accordance with one embodiment of the present invention. The stent 10is representative of a medical device that is suitable for having acoating applied thereon to effect a therapeutic result. The stent 10 isformed of a series of interconnected struts 12 having gaps 14 formedtherebetween. The stent 10 is generally cylindrically shaped.Accordingly, the stent 10 maintains an interior surface 16 and anexterior surface 18. FIG. 10E illustrates a coated surgical mesh,represented as a biocompatible mesh structure 10, in accordance with oneembodiment of the present invention. The biocompatible mesh structure 10is flexible, to the extent that it can be placed in a flat, curved, orrolled configuration within a patient. The biocompatible mesh structure10 is implantable, for both short term and long term applications.Depending on the particular formulation of the biocompatible meshstructure 10, the biocompatible mesh structure 10 will be present afterimplantation for a period of hours to days, or possibly months, orpermanently.

Each of the medical devices illustrated, in addition to others notspecifically illustrated or discussed, can be combined with the coating10 using the methods described herein, or variations thereof.Accordingly, the present invention is not limited to the exampleembodiments illustrated. Rather the embodiments illustrated are merelyexample implementations of the present invention.

In another embodiment, the biomaterials of the invention, i.e., apre-cure biomaterial, or a fatty acid-based, pre-cure-derivedbiomaterial can be used in the form of an emulsion. An “emulsion,” whichis a type of suspension, is a combination of two or more immiscibleliquids in a particular energetically unstable state. Although anemulsion can be a combination of more than two immiscible liquids, forthe sake of clarity, the following explanation will be presentedassuming an emulsion of only two liquids. The first liquid is dispersedor suspended in a continuous phase of the second liquid. This may bethought of as “droplets” of the first suspended liquid distributedthroughout a continuous “pool” of the second liquid. The first liquidcan include a mixture of any number of miscible liquids and the secondliquid can include a mixture of any number of miscible liquids as longas the mixture of the first liquid is immiscible with respect to themixture of the second liquid. One of ordinary skill in the art willappreciate that emulsions can be formulated using a combination of threeor more immiscible liquids, and although such embodiments are notdescribed further herein, they are considered to fall within the scopeof the present invention.

Various aspects and embodiments of the present invention are furtherdescribed by way of the following Examples. The Examples are offered byway of illustration and not by way of limitation.

EXAMPLES

The following examples characterize the novel fatty acid-derivedbiomaterial chemistry described herein and illustrate some of theboundaries associated with the chemical mechanisms of formation and howalteration of those mechanisms influences the properties (e.g.,therapeutic benefits and/or drug release profile) of the final product.The identity of some of the hydrolysis products are identified throughin-vitro experiments and correlated with in-vivo experiments todemonstrate the ability for the coating or stand-alone film to bebioabsorbed. Finally, examples showing the utility of the fattyacid-derived biomaterials described herein in drug delivery applicationson coronary stents and hernia mesh devices are presented.

The following examples are for demonstration purposes and are not meantto be limiting.

Example 1 Analysis of In-Vitro Hydrolysis Chemistry of a NovelBiomaterial Derived from Fish Oil in 0.1 M PBS Solution

In the following example, coated medical devices (e.g., a polypropylenemesh) were cured in a high airflow oven at 200° F. for 24 hours, afterwhich the fish oil was converted into a cross-linked biomaterial gelcoating encapsulating the polypropylene mesh by oxidation of the C═Cbonds present in the fish oil resulting in the formation of oxidativebyproducts (i.e., hydrocarbons, aldehydes, ketones, glycerides, fattyacids) while largely preserving the esters derived from the original oiltriglycerides. Volatilization of the byproducts followed by theformation of ester and lactone cross-links result in the solidificationof oil into a bioabsorbable hydrophobic cross-linked biomaterial. Theability for the coating to be slowly hydrolyzed was investigated using0.1 M PBS solution. The PBS solution was analyzed using GC-FID fattyacid profile and GPC chromatographic measurements after hydrolysis ofthe oil-derived biomaterial in PBS for 30 days.

FIG. 11 summarizes the fatty acid profile results obtained after dryingthe PBS solution and then performing a GC-FID fatty acid profileanalysis as described in the AOCS official method Ce 1-89b to identifythe fatty acids present in solution. FIG. 11 shows that the fatty acidsidentified from the PBS solution are the same as those detected from thecoating itself. GPC analysis was also conducted on the hydrolysissolution and the results are summarized in Table 5. The GPC resultsshowed that the vast majority of molecular weight components identified(80%) were below a molecular weight of 500, which is consistent with thefatty acid components of the coating. Also, glyceride components of thecoating could be identified with molecular weights around 1000 (15% ofthe coating). The GPC results also showed a negligible amount(approximately 4%) of high molecular weight gel. The GPC results supportthe other analytical characterization experiments on the oil-derivedcoatings which show that the oil-derived biomaterial is comprised ofcross-linked glycerides and fatty acids, and that the majority of thecoating is non-polymeric (i.e., approximately 80% of the componentsidentified had a molecular weight of less than 500).

TABLE 5 GPC Analysis of PBS Hydrolysis Solution after Contact with FishFatty acid-Derived Biomaterial for 30 days. Molecular Weight % Peak AreaPotential Identity >110,000 4 High Molecular Weight Gel >1000 1Partially Hydrolyzed Gel 1000 15 Glycerides <500 80 Fatty Acids

Example 2 Fatty Acid Based, Pre-Cure Derived Coatings Loaded withTherapeutics and Applied to Metallic Stents

In this particular embodiment of the present invention, the applicationof cured oil coatings loaded with a therapeutic and applied to a cardiacstent are presented. The flow diagram presenting the process to create acured coating on a stent loaded with a therapeutic is outlined in FIG.13. Briefly, a pre-cured fish oil coating is created in a reactionvessel under agitation with heating in the presence of oxygen at 200° F.for 20 hours. The coating is mixed with the therapeutic of interest, andvitamin E with a solvent and then sprayed onto the stent to create acoating. The coating is annealed to the stent surface by heating at 200°F. for 7 hours to create a uniform coating. A coating with a modelanti-inflammatory agent showed that this process allowed for 90% of thedrug to be recovered after curing as determined using extraction of thedrug from the device with HPLC analysis. FIG. 14 shows the drug releaseprofile for this coating in 0.01 M PBS buffer going out to 20 days withover a 90% recovery of the drug using this process.

Example 3 Controlled Release of the Fatty Acid Based, Pre-Cure DerivedCoating

Drug release was quantified for 3 batches of 16 mm stainless steelstents, coated with a Compound C drug coating formulation consisting of60% Compound C, 30% pre-cured Fish Oil, 10% tocopherol Pre-cured fishoil was produced using fish oil, pre-cured at 93° C., to achieve apre-cure viscosity of 1.3×10⁵ cps as measured at 22° C. The coating wasapplied to surface of a 16 mm Atrium Flyer stainless steel stent byspraying to achieve an overall stent drug load of approximately 100 μgof Compound C per stent. The coated stents were subjected to a secondthermal cure process whereby the coating was post-cured in an oven at93° C. for a period of 7.5 hours. Dissolution was carried out in a 4 mlsolution containing 0.01M purified buffered saline (PBS) at atemperature of 37° C.

An HPLC method was used to quantify drug dissolution in vitro of theCompound C drug coated stent. The drug release profile data is shown inFIG. 15, which illustrates that the drug release from the Compound Cdrug coating extends over a period of 20 days and that the releaseprofile is reproducible from batch to batch.

Example 4 Trackability Forces for Bare Metal, Coated and Drug CoatedStent

Device trackability forces were quantified for 3.0 mm×13 mm CoCr stentsmounted on a balloon catheter. Trackability forces were quantified for 3distinct stent coating groups, a bare metal CoCr stent, a CoCr stentcoated with a 75% pre-cured fish oil, 25% tocopherol coating and a CoCrstent coated with a 60% Compound B, 22.5% pre-cured fish oil, 12.5%tocopherol coating. Pre-cured fish oil was produced using fish oil,pre-cured at 93° C., to achieve a pre-cure viscosity of 1.0×10⁶ cps asmeasured at 22° C. The fatty acid-derived, pre-cured biomaterial wasprepared by dissolving 75% pre-cured fish oil with 25% tocopherol inMTBE solvent to achieve a 1% solids formulation. The formulation isvortexed for 1 minute at 3000 RPM. The formulation is then applied tothe stent via a spray process to achieve a total stent coating weight ofapproximately 167 μg. The coated stents are subjected to thermalpost-curing at 93° C. for 6 hours. Following the post-curing process,the stents are crimped onto balloon catheters to achieve a stent profiledimension of approximately 0.04 inches using a 12 point crimpinginstrument exerting compressive loads of between 16 and 22 psi. TheCompound B, pre-cured fish oil, tocopherol formulation was prepared bydissolving 75% pre-cured fish oil with 25% tocopherol in MTBE solvent toachieve a 25% solids formulation. A quantity of Compound B is weighedout in a proper glass vial and a volume of the pre-cured FO andtocopherol formulation is added into the glass vial to achieve a 60%Compound B, 40% pre-cure fish oil-tocopherol ratio. Additional MTBE isadded to the glass vial to achieve a total solids ratio of 1%. Theformulation is vortexed for 1 minute at 3000 rpm. The formulation isthen applied to the stent via a spray process to achieve a total stentcoating weight of approximately 167 μg. The coated stents are subjectedto thermal post-curing at 93° C. for 6 hours. Following the post-curingprocess, the stents are crimped onto balloon catheters to achieve astent profile dimension of approximately 0.04 inches. Catheters withstents mounted over the balloon segment are then threaded through a 6FrMedtronic Launcher guide catheter inserted within a torturous pathconsisting of an anatomical model containing 2 bends having radii of 22mm and 14 mm with a total set travel distance of 395 mm. De-Ionizedwater was used as the test environment. Forces are measured by a loadcell on the mechanism used to drive the catheter forward.

Trackability force data is shown in FIG. 16. This data indicates loweroverall trackability forces required to push the devices incorporatingthe fatty acid-derived, pre-cured biomaterial coating containingtocopherol, Compound B and pre-cured fish oil as compared to the baremetal stent, suggesting that the coatings substantially reduce thecoefficient of friction of the stent surface and subsequently thefrictional forces between the stent and the guide catheter wall duringthe process of advancing the balloon catheter within the guide catheterthrough a torturous pathway.

Example 5 Post Curing Time and Temperature Affects on MechanicalProperties

The effects of post curing time and temperature on coating mechanicalproperties were evaluated in a study in which CoCr stents were coatedwith an oil-derived, pre-cured biomaterial coating of CompoundB/pre-cured fish oil/tocopherol. CoCr stents were pre-cleaned withacetone, and coated with a formulation of 60% Compound B, 30% pre-curedfish oil, 10% tocopherol. The Compound B, pre-cured fish oil, tocopherolformulation was prepared by dissolving 75% pre-cured fish oil with 25%tocopherol in MTBE solvent to achieve a 25% solids formulation. Aquantity of Compound B is weighed out in a glass vial and a volume ofthe pre-cured FO and tocopherol formulation is added into the glass vialto achieve a 60% Compound B, 40% pre-cure fish oil-tocopherol ratio.Additional MTBE is added to the glass vial to achieve a total solidsratio of 1%. The formulation is vortexed for 1 minute at 3000 RPM. Theformulation is then applied to the stent via a spray process to achievea total stent coating weight of approximately 167 μg. The coated stentswere then subjected to thermal post-curing process at temperaturesranging from 60° C. to 100° C.

Following the post-curing process, the stents are crimped onto ballooncatheters using a twelve point crimping instrument to achieve a stentprofile dimension of approximately 0.043 inches, requiring 16-22 psi ofcrimping pressure. Subsequently, the balloon catheters were inflated inair to a nominal inflation pressure of 9 atm. Following crimping andexpansion the drug coating is evaluated visually for physical damage.The results of this testing demonstrate that stents post cured attemperatures above 80° C. show substantially less coating damagefollowing crimping and subsequent expansion than stents post cured at80° C. or less, demonstrating that mechanical properties of the coatingcan be significantly altered by changing the final cross link density ofthe coating by altering the temperature at which the coating is postcured.

Example 6 Influence of Curing Time and Temperature on Drug Recovery ofThermally Sensitive Drugs

The effect of curing time and temperature on drug recovery of athermally sensitive drug incorporated within hydrophobic cross linkedgel coating was evaluated and quantified. Pre-cured fish oil (PCFO) wasprepared by heating fish oil in a reactor at 93° C. for a total of 26hours, while infusing oxygen through a diffuser. The resultant viscosityof the pre-cured fish oil was 5×10⁶ cps as measured at 22° C. Theformulation consisting of 60% Compound B, 30% PCFO, and 10% Vitamin Ewas made by combining 3.76 g PCFO and 1.3 g Vitamin E to form a 75%PCFO, 25% Vitamin E base coating. 15.04 g methyl-tert-butyl-ether (MTBE)was added to produce a base coating solution of 75% solvent, 25% solids.This solution was vortexed for 30 min until clear. Next, 529 mg of thebase coating solution was added to 198.8 mg Compound B. This mixture wasdiluted with 32.8 g methyl-tert-butyl-ether (MTBE) to produce a finalsolution of 1.0% solids for spray coating. CoCr stents (3.0×13 mm) werespray coated using an ultrasonic spray coating system (SonoTek, Inc.)with a target load of 100 μg Compound B. Each coated stent was weighedbefore coating and after coating to determine the actual weight ofcoating applied to each stent gravimetrically. Coated stents weresubjected to oven post curing at a temperature range between 60° C. to100° C. with post curing time ranging from 0 hrs to 24 hours. Followingpost curing the drug coating was extracted in a 100% acetonitrilesolution and analyzed via HPLC to determine the drug concentration insolution from which the total drug mass extracted from the stent isdetermined. The total drug mass extracted from the stents along with theactual coating weight on the stent determined gravimetrically is used tocalculate the percent of drug applied to the stent in coating which isrecovered following the post curing process. Percent drug recovery datais shown in FIG. 18. This data illustrates that 100% of the drug isrecovered after spray coating the stent and prior to post curing.However, drug recovery drops with post curing and as post curing timeincreases. The data also shows that the rate at which drug recoverydrops over time is directly influenced by the temperature at which postcuring is carried out.

Example 6A Influence of Curing Time on the Crosslink Density of aPre-Cured Fish Oil as Measured by Viscosity

The effect of curing time on pre-cured fish oil viscosity was evaluatedand quantified. Pre-cured fish oil (PCFO) was prepared by heating fishoil (Ocean Nutrition 18/12TG fish oil) in a reactor at 93° C. for atotal of 33 hours, while infusing oxygen through a diffuser. During thisreaction, oxidation of the oil occurs and cross links are formed. Theduration of the reaction directly influences the extent of oxidation andcross linking that occurs, and results in an increase in viscosity ofthe oil over time during the reaction. Thus the final viscosity of thepre cured fish oil can be correlated to the extent of cross linking andoxidation. Fish oil was reacted at 93° C. with oxygen for 23 h, 26 h,30.5 h, and 33 h. Viscosity was measured at 22° C. The results (FIG. 19)show an increase in viscosity corresponds to longer reaction times andthus indirectly confirm that increase crosslink density associated withhigher viscosities also increases with the time of curing.

Example 7 Method of Producing a Fatty Acid Based, Pre-Cure DerivedCoating on a Stent Using the Therapeutic Agent Compound C

Pre-cured fish oil (PCFO) was prepared by heating fish oil (OceanNutrition 18/12TG fish oil) in a reactor at 93° C. for a total of 23hours, while infusing oxygen through a diffuser. The resultant viscosityof the pre-cured fish oil was 1×10⁶ cps as measured at 22° C. TheCompound C drug coating formulation consisting of 70% Compound C, 22.5%PCFO, and 7.5% Vitamin E (DSM Nutritional Products) was made bycombining 3.7561 g PCFO and 1.2567 g Vitamin E to form a 75% PCFO, 25%Vitamin E base coating. 15.04 g methyl-tert-butyl-ether (MTBE) was addedto produce a base coating solution of 75% solvent, 25% solids. Thissolution was vortexed for 30 min until clear. Next, 767.6 mg of the basecoating solution was added to 447.8 mg Compound C. This mixture wasdiluted with 7.84 g methyl-tert-butyl-ether (MTBE) to produce a finalsolution of 7.6% solids for spray coating. Atrium Cinatra™ CoCr stents(3.5×13 mm) were spray coated using a Badger airbrush equipped with amedium sized needle. The target coating load was 100 μg Compound C perstent. Each stent was spray coated for 1.5 seconds using an air pressureof 30 psi, while the stent was rotated. This yielded an average coatingload of 95.2 μg Compound C. Coated stents were cured in an oven set to93° C. for 7 hours. This process yields a conformal stent coating havinga smooth surface characteristic when imaged using scanning electronmicroscopy (SEM). FIG. 20A is an SEM of the Compound C drug coated stentat 50× magnification following 7 hours of post curing at 93° C.

Example 8 Method of Producing a Fatty Acid Based, Pre-Cure DerivedCoating on a Stent Using Therapeutic Agent Compound B

Pre-cured fish oil (PCFO) was prepared by heating fish oil (OceanNutrition 18/12TG fish oil) in a reactor at 93° C. for a total of 23hours, while infusing oxygen through a diffuser. The resultant viscosityof the pre-cured fish oil was 1×10⁶ cps. The formulation consisting of60% Compound B, 30% PCFO, and 10% Vitamin E (DSM Nutritional Products)was made by combining 3.7582 g PCFO and 1.2562 g Vitamin E to form a 75%PCFO, 25% Vitamin E base coating. 15.04 g methyl-tert-butyl-ether (MTBE)was added to produce a base coating solution of 75% solvent, 25% solids.This solution was vortexed for 30 min until clear. Next, 529 mg of thebase coating solution was added to 198.8 mg Compound B. This mixture wasdiluted with 32.8 g methyl-tert-butyl-ether (MTBE) to produce a finalsolution of 1.0% solids for spray coating. CoCr stents (3.0×13 mm) werespray coated using an ultrasonic spray coating system (SonoTek, Inc.)with a target load of 100 μg Compound B. Coated stents were cured in a93° C. oven for 6 hours. This process yields a conformal stent coatinghaving a smooth surface characteristic when imaged using scanningelectron microscopy (SEM). FIG. 20B is an SEM of the Compound B drugcoated stent at 50× magnification following 6 hours of post curing at93° C.

Example 9 Simulation of the Chemical Effects of the Fatty Acid Based,Pre-Cure Derived Stent Coating Process on Individual FormulationComponents

Each individual formulation component (i.e., pre-cured fish oil, vitaminE, and Compound B) was studied before and after final curing tounderstand the effects of the process on the chemistry of the Compound Boil-derived, pre-cured biomaterial coating. In this set of experiments,each individual component was sprayed on coupons after being diluted inmethyl-tert-butyl-ether (MBTE) to mimic coated stents. The separatecomponents were analyzed using appropriate spectroscopic andchromatographic techniques before and after final curing at 200° F. forsix hours.

The effects of dissolving pre-cured fish oil into MTBE solvent andspraying it onto a stainless steel coupon before and after final curingusing FTIR analysis is presented in FIGS. 21A, 21B, and 21C. FTIRanalysis of the pre-cured fish oil before and after curing reveals thatthe double bonds in the oil are oxidizing and forming lactone/estercross-links resulting from the 6 hr curing process. Oxidation isevidenced by an increase in OH band absorption and a decrease in the cisand trans C═C peaks (FIGS. 21A and 21C), and broadening of the carbonylpeak indicating the formation of carbonyl byproducts (FIG. 21B).Evidence of cross-linking in the final cure is observed by the increasein the lactone/ester peak absorption band (FIG. 21B). GC fatty acidprofile analysis of coupons is also consistent with oxidation of the oilbefore and after the final curing process. FIG. 22 presents the fattyacid compositional profile of pre-cured fish oil sprayed onto couponsbefore and after the curing process. The GC fatty acid profile resultsshow a shift in the profile showing a reduction of unsaturated fattyacids and an increase in the saturated fatty acids after final curing(FIG. 22), which is consistent with oxidation of the unsaturated fattyacids. This result is also reflected in the pre and post curing GCchromatograms where the C16:1 and C18:1 unsaturated fatty acids peaksare reduced in the chromatogram (FIG. 23).

FTIR spectra of vitamin E dissolved in MTBE and sprayed onto couponswith and without final curing are presented in FIGS. 24A, 24B and 24C.FTIR results show that the final curing process results in oxidationwhich is supported by the formation of a peak at 1800-1600 cm⁻¹ (FIG.24C). This result is further supported by the loss of the phenol OHabsorption band after the final curing step (FIG. 24B), which occursafter oxidation of vitamin E. The vitamin E coated onto coupons beforeand after curing was extracted off the coupons and assayed by HPLC(Table 8). Each test represents an average of three samples. The resultsof this study show that when vitamin E is cured (i.e., oxidized) therecovery is reduced to 81%. HPLC chromatograms of a vitamin E controloverlaid with vitamin E sprayed onto coupons before and after curing at292 nm are presented in FIGS. 25A, 25B and 25C.

TABLE 8 Summary of Vitamin E HPLC Assay Results Sample Description %Recovery Vitamin E sprayed onto coupon in 96.2 MTBE. Vitamin E sprayedonto coupon in 80.5 MTBE, after final cure.

FTIR analysis of Compound B drug powder after spraying onto couponsbefore and after curing is presented in FIGS. 26A, 26B and 26C. FTIRreveals that dissolving Compound B in MBTE solvent and spraying it ontothe coupons changes the conformation of the drug's structure incomparison to the control drug power spectrum. Specifically, the FTIRresults show that following the spray process the amide band is shiftedto the left and showing beginning signs of peak splitting in comparisonto the Compound B powder control (FIG. 26B). This appears to correlatewith the peak at ˜1375 cm⁻¹ in the fingerprint region that has changedshape in comparison to the control sample (FIG. 26C, Peak1). There isalso a peak that is formed that is not present in the control sample at˜1280 cm⁻¹ (FIG. 26C, Peak2). Following the curing of the Compound Bsamples several other spectral changes can be noted. The carbonyl bandmerges from two peaks into one peak (FIG. 26B). This peak issignificantly broader than the Compound B powder control (FIG. 26B).Furthermore, the C—O peak at ˜1025 cm⁻¹ disappears following the curingprocess (FIG. 26C, Peak3). These changes indicate a structural change inthe Compound B as a result of curing. There is a change in the trans C═Ctriene peak at about 990 cm⁻¹ where it is greatly reduced in intensityafter curing (FIG. 26C), which indicates that oxidation of the CompoundB occurred. These changes indicate a structural change in the Compound Bstructure.

Assay of the Compound B drug load by HPLC reveals an equal recovery ofthe Compound B before and after spraying the Compound B onto coupons,before final curing. Upon inspection of the native chromatogram (FIG.27B) there does not appear to be any significant degradation productsformed after spraying. (FIG. 27A is the control.) However, following thecuring process, the Compound B drug powder recoveries is reduced toapproximately 9% (Table 9) and several new byproduct peaks are formed asdetected by HPLC (FIG. 27C). These results are consistent with the FTIRdata presented in FIG. 26C, which indicates that a degradation of theCompound B occurred after the final curing process.

TABLE 9 Summary of Compound B HPLC Assay Results % Sample DescriptionRecovery Compound B Powder 96 Control Compound B sprayed 90.6 ontocoupon in MTBE, no final cure. Compound B sprayed 8.9 onto coupon inMTBE, after final cure.

In summary, these studies showed that cured separately each component ofthe oil-derived biomaterial coating was oxidized during the curingprocess and specifically the Compound B therapeutic compound not in anoil-derived stent coating formulation was significantly degraded as aresult of the curing process. This evidences the protective nature ofthe pre-curing process described herein in accordance with the presentinvention.

Example 10 Analysis of the Compound B Fatty Acid Based, Pre-Cure DerivedCoating Formulation Components Combined and Sprayed onto Coupons

In this series of experiments the changes in chemistry for eachcomponent in the Compound B oil-derived, pre-cured biomaterial coatingwas studied. The components were mixed together, sprayed onto coupons,and subjected to different stages of the stent coating manufacturingprocess. The 60% Compound B in 30% pre-cured fish oil, and 10% vitamin Ewas dissolved into MTBE and spray coated onto coupons. Samples wereanalyzed before and after final curing at 93° C. for 6 hours. FTIR,HPLC, and GC analyses were performed on the coatings. FIGS. 28A, 28B and28C present the FTIR spectra of the Compound B oil-derived, pre-curedbiomaterial coating before and after final curing. Interestingly, thereare few spectral changes in the spectrum after final curing, especiallyin functional groups assigned to the Compound B therapeutic compound.Specifically there are no apparent intensity changes in the trans C═Cband and there does not appear to be any significant changes instructure in the FTIR fingerprint region (FIG. 28C). The biggestdifference in the Compound B biomaterial coating after heating is anincrease in absorption around 1780 cm⁻¹, which is consistent withlactone/ester cross-linking of the fish oil component of the curing, andwhich was also observed with the fish oil by itself after curing (FIG.21B). These results contrast those results obtained for the Compound Bpowder alone where significant structural changes were noted after finalcuring (FIG. 26) and show that Compound B is more chemically stablemixed in the oil-derived biomaterial formulation.

Further evidence for the preservation of the drug structure in theCompound B is shown by the Compound B HPLC assay results presented inTable 10. The average Compound B recovery in formulation isapproximately 62% on coupons where it was only approximately 9% whenonly present as a drug powder. Average vitamin E recovery in thecoating, however, trends lower from 81% by itself after final cure downto 68% in formulation. Analysis of the Compound B HPLC chromatogramsfrom the fatty-acid based, pre-cure-derived coating formulationindicates that drug degradation is greatly reduced in comparison to thedrug only results (FIG. 27C versus FIG. 29B).

GC fatty acid compositional analysis of the Compound B oil-derivedbiomaterial formulation before and after final curing revealed thatthere was a marked reduction of oxidation of the fatty acids in the fishoil in formulation in comparison to when cured by itself (FIG. 23 versusFIG. 30). Because vitamin E is an antioxidant (i.e., oxidizes at afaster rate than fish oil) this result is not unexpected. The inhibitionof oxidation of the unsaturated fatty acids of the oil component is alsoobserved in the native GC chromatogram before and after final curing(FIG. 12).

TABLE 10 Summary of Compound B HPLC Assay Results % Standard SampleDescription Recovery Deviation % RSD Compound B Powder Control 96 0.040.04 Compound B in 75:25 pre-cured 97.8 0.97 0.99 fish oil:vitamin Ewith MTBE sprayed onto coupon without final cure. Compound B in 75:25pre-cured 61.9 14.78 23.86 fish oil:vitamin E with MTBE sprayed ontocoupon after final cure.

Example 11 In-Situ Kinetic Analysis of Compound B Fatty Acid Based,Pre-Cure Derived Coating Using FTIR, and HPLC Analysis

In this experiment, 60% Compound B in 30% pre-cured fish oil, andvitamin E was dissolved into MTBE and spray coated onto 3.5×13 mm cobaltchromium stents in order to correlate the model coupon experiments inExamples 3 and 4 to the Compound B oil-derived biomaterial stent coatingprocess. The coated stents were placed in the oven to cure at 200° F.and samples were removed every hour of the 6 hour curing process. FTIRspectroscopic analysis was performed at every time point. Compound B andvitamin E HPLC assay testing was performed at T=0, 3, and 6 hr curingpoints.

FTIR analysis performed at various time points (FIGS. 31A, 31B and 31C)revealed a similar trend in final chemistry to those obtained for theCompound B oil-derived formulation on coupons (FIG. 28). Specifically,only small shifts in absorption bands could be noted, but no extremeloss in Compound B structure was noted in comparison to the Compound Bdrug powder FTIR coupon experiments (FIG. 26 versus FIG. 31). HPLC assaytesting performed on the stent samples at T=0, 3, and 6 hrs for theCompound B is presented in FIG. 17. The Compound B shows decreasedrecovery as a function of cure time with final curing recovery averaging75% for Compound B due to oxidation of the drug, but to a much lessdegree than the Compound B drug powder subjected to heating alone, whichonly yielded a 9% recovery. The vitamin E assay results trend similarlyto the Compound B where there is a decrease in recovery as a function oftime with a final recovery of 69% being obtained.

Example 12 Summary of Mechanism of Fatty Acid Based, Pre-Cure DerivedStent Coating Formation

From the experiments performed in Examples 11-13 several conclusions canbe drawn from the data to elucidate the chemistry of formation of theCompound B oil-derived, pre-cured biomaterial stent coating. In Example11, each formulation component in MTBE was sprayed onto coupons and thenpost cured onto the coupon surface in order to determine the changes inchemistry for each component in the process. Analysis of the pre-curedfish oil only coupons revealed that final curing further oxidizes thedouble bonds present, as no cis C═C bonds are retained. Additionallactone cross-linking and carbonyl byproduct formation are detected. GCfatty acid profile analysis of the pre-cured fish oil only couponsbefore and after post-curing was also consistent with oxidation of thefish oil fatty acid double bonds. FTIR analysis of the vitamin E onlycoupons also determined that the final curing process resulted inoxidation of the vitamin E. This was evidenced by the formation of avitamin E byproduct peak in the carbonyl absorption region and a loss ofthe phenol OH absorption band. Oxidation was confirmed by HPLC assay,which showed a 20% loss of vitamin E recovery after final curing.Finally, testing of the Compound B drug powder sprayed onto couponsshowed that that dissolving the drug in solvent and spraying it onto thecoupons is changing the Compound B structure when compared to thecontrol powder spectrum (i.e., shift in amide absorption band). Afterfinal cure the Compound B drug powder chemical structure issignificantly altered as evidenced by several absorption mode changes byFTIR, only 9% recovery of the Compound B was obtained by HPLC assay, andbyproduct peaks indicating degradation were present in the HPLCchromatogram. Although the results of these studies clearly showoxidation of the vitamin E, pre-cure fish oil, and Compound B drugpowder components through the final curing process, these resultssuggest that that there is an additional interaction between theformulation components (i.e., vitamin E and pre-cured fish oil) whenmixed together then when subjected to the final curing process astypical Compound B HPLC assay results range between 75-85% recovery ofthe Compound B from oil-derived stent coatings.

In the second group of experiments, the Compound B, pre-cured fish oiland vitamin E were mixed in MTBE and sprayed onto coupons, and sampleswere analyzed before and after the final post-cure process step. Thesedata revealed a significant increase in the preservation of the drugstructure as evidenced in the FTIR spectra and the greater of recoveryof drug from the coating (i.e., ˜62%) as determined by HPLC assay.Byproduct peaks for the Compound B were still detected by HPLC, but weremuch less intense than those detected when the drug was subjected to thefinal post-cure process by itself. The pre-cured fish oil, whenformulated with vitamin E, showed a decrease in oxidation in formulationwhen compared to the pre-cured fish oil with no vitamin E as detected inGC fatty acid compositional analysis (FIG. 23 vs. FIG. 12). However,lactone/ester cross-linking was still observed.

In general, the results obtained from the stent studies mirrored thoseobtained from the coupon formulation studies, except that the averageCompound B recovery was increased to 75%.

Based on the experiments conducted in this study several conclusions canbe obtained. After spraying, the coating applied to the stent appearsnon-uniform and after heating the coating spreads across the surface ofthe stent, the pre-cured fish oil cross-links, and a uniform coating isproduced. The recovery of the Compound B from formulation issignificantly greater than the recovery obtained when assaying theCompound B by itself (9%), showing that the formulation (i.e., VitaminE) is providing some protection to the drug stability.

Analysis of the vitamin E in formulation showed that it is oxidizing asa result of the final curing process using both FTIR and HPLC testing,but the pre-cured fish oil is less oxidized as detected by GC fatty acidprofile. Similar to the Compound B analytical data, this resultindicates that the vitamin E is providing protection to the oil duringthe oxidation process. However, despite the presence of the vitamin E,lactone/ester cross-linking in the fish oil component in formulation oncoupons after final curing could still be detected. Lactone/estercross-linking can still occur in the oil-derived biomaterial coatingbecause the fish oil used in the formulation is pre-cured before use.Partially curing the fish oil creates carboxyl and hydroxyl functionalgroups that are needed to form lactone/ester cross-links, and thus thepresence of the vitamin E in the final curing step only serves to reduceadditional oxidation, but cannot reverse the oxidation or the molecularspecies already formed in the pre-cured oil.

As can be seen, by, for example, preserving the structure of thetherapeutic agent, the therapeutic agent will have an enhanced releaseprofile when released from the coating.

Example 13 Method of Producing a Fatty Acid Based, Pre-Cure DerivedCoating on a Stent Using Compound E

Pre-cured fish oil (PCFO) was prepared by heating fish oil in a reactorat 93° C. for a total of 23 hours, while infusing oxygen through adiffuser. The resultant viscosity of the pre-cured fish oil was 1×10⁶cps. The coating formulation consisting of 70% Compound E, 22.5% PCFO,and 7.5% Vitamin E was made by combining 18.5 mg PCFO, 6.4 mg Vitamin E,57.9 mg Compound E, and 8.20 g of methyl-tert-butyl-ether (MTBE) (SigmaChemicals) to produce a coating solution having of 99% solvent, 1%solids for spray coating. This solution was vortexed for 30 min untilclear. Atrium Cinatra™ CoCr stents (3.5×13 mm) were spray coated using aSonoTek Medicoat DES 1000 ultrasonic Spray System. The target coatingload was 100 μg Compound E per stent with an actual coating weight of133.28 μg, which results in a calculated drug load of 93.2 μg based uponthe calculated final drug fraction in the coating. Coated stents werecured in an oven set to 93° C. for 6 hours. This process yields a dry,non-tacky, conformal stent coating having a smooth surfacecharacteristic when imaged using scanning electron microscopy (SEM).

In a related but separate experiment, 20 μL of the same drug coatingformulation described above was pipetted onto Cobalt Chromium couponswith a target drug load of 100 μg of Compound E. The coated coupons werepost cured in an oven at 93° C. for 6 hours. Gravimetric measurements ofthe coated coupons following the final 6 hour post curing processdemonstrated an average coating load of 152.603 μg which based upon acalculated drug fraction of 69.92% Compound E results in an average drugload per coupon of 106.7 μg of Compound E. Following post curing thedrug coating was extracted from the coupon in a 100% acetonitrilesolution and analyzed via HPLC to determine the drug concentration insolution, from which the total drug mass extracted from the coupon wasdetermined. The total drug mass extracted from the coupons along withthe actual coating weight on the coupon determined gravimetrically isused to calculate the percent of drug applied to the coupon in coatingwhich is recovered following the post curing process. The percent drugrecovery from coating cured on the CoCr coupons for 6 hrs at 93° C. wascalculated to be 96.7%. The drug recovery data clearly shows that thedrug integrity is preserved through the coating formulation, applicationand most importantly the thermal post curing process.

Example 14 Method of Producing a Fatty Acid Based, Pre-Cure DerivedCoating on a Stent Using Therapeutic Agent Compound D

Pre-cured fish oil (PCFO) was prepared by heating fish oil in a reactorat 93° C. for a total of 23 hours, while infusing oxygen through adiffuser. The resultant viscosity of the pre-cured fish oil was 1×10⁶cps. The Compound D drug coating formulation consisting of 50% CompoundD, 37.5% PCFO, and 12.5% Vitamin E was made by combining 55.4 mg PCFO,18.5 mg Vitamin E, 74.3 mg Compound D, and 14.67 g solvent solutionconsisting of 60% methyl-tert-butyl-ether (MTBE) 40% acetone to producea coating solution having 99% solvent, 1% solids for spray coating. Thissolution was vortexed for 30 min until clear. Atrium Cinatra™ CoCrstents (3.5×13 mm) were spray coated using a SonoTek Medicoat DES 1000ultrasonic Spray System. The target coating load was 100 μg Compound Dper stent with an actual coating weight of 164.16 μg, which results in acalculated drug load of 82.3 μg based upon the calculated final drugfraction in the coating. Coated stents were cured in an oven set to 93°C. for 6 hours. This process yields a dry, non-tacky, conformal stentcoating having a smooth surface characteristic when imaged usingscanning electron microscopy (SEM).

In a related but separate experiment, 40 μL of the same drug coatingformulation described above was pipetted onto Cobalt Chromium couponswith a target drug load of 100 μg of sirolimus drug. The coated couponswere post cured in an oven at 93° C. for 6 hours. Gravimetricmeasurements of the coated coupons following the final 6 hour postcuring process demonstrated an average coating load of 305.59 μg whichbased upon a calculated drug fraction of 50.13% sirolimus results in anaverage drug load per coupon of 153.1 μg of sirolimus. Following postcuring the drug coating was extracted from the coupon in 80% methanol,20% (0.2% acetic acid) solution and analyzed via HPLC to determine thedrug concentration in solution, from which the total drug mass extractedfrom the coupon was determined. The total drug mass extracted from thecoupons along with the actual coating weight on the coupon determinedgravimetrically is used to calculate the percent of drug applied to thecoupon in coating which is recovered following the post curing process.The percent drug recovery from coating cured on the CoCr coupons for 6hrs at 93° C. was calculated to be 71.5%. The drug recovery data clearlyshows that the drug integrity is preserved through the coatingformulation, application and most importantly the thermal post curingprocess. Although the sirolimus drug recovery is less than 100% in thisexample, the recovery is far better than the near zero percent recoveryobtained when the pre-curing of the fish oil step is removed and allcoating curing occurs in the final coating with the drug included.

Example 15 In-Vivo Performance and Biological Response of a CoronaryStent Coated with a Cross Linked Fatty Acid Based Coating Incorporatinga Therapeutic Agent

In this study, a coating formulation containing 50% Compound D, 37.5%pre-cured fish oil and 12.5% tocopherol was prepared using pre-curedfish oil having a viscosity of 1×10⁵ cps, as measured at 25° C. Thecoating formulation was subsequently sprayed onto 3.0 mm×13 mm and 3.5mm×13 mm Atrium Cinatra CoCr stents using a Badger airbrush equippedwith a medium sized needle. Following the spray coating application ofthe coating to the stents, the coated stents were oven post cured at 93°C. for 6 hours to achieve a uniform and conformal drug coating layer.The final drug load per stent, as measured by HPLC, was 68 μg ofCompound D. Following post curing, coated stents were crimped onto 3.0mm×14 mm and 3.5 mm×14 mm PTCA catheters respectively, the devices weresubsequently packaged and sterilized via e-beam sterilization with anominal dose of 35 kgy. The sterile drug coated stent devices were thenused to conduct a pre-clinical study in a porcine model, where by singlestents were implanted into three coronary vessels, the Left AnteriorDescending Artery (LAD), the Left Circumflex Artery (L CX) and the RightCoronary Artery (RCA) of the porcine heart. Three groups of stents wereimplanted: 1) Bare metal stents, 2) stents with coating alone (no drug)and 3) drug coated stents (DCS) to assess their comparative biologicalresponse. All stents were implanted with an appropriate expansion toachieve a stent to vessel diameter ratio of 1.10:1. Post implantation,animals were recovered and were maintained for 28±2 days, at which timethe animals were sacrificed and the hearts harvested and fixed informalin. Following fixation, the stented vessels were isolated anddissected from the heart. The stented arteries were dissected andembedded in methylmethacrylate for sectioning and histopathologicevaluation. Sections were taken from the proximal portion, mid portion,and distal portion of each stent. The images in FIG. 32 arerepresentative vessel cross sections having a BMS stent. The images inFIG. 33 are representative vessel cross sections having a stent withcoating alone (no drug). The images in FIG. 34 are representative vesselcross sections having a DCS stent. As can be seen in these comparativeimages there is no notable difference in the overall tissue reactionamong the three groups with the exception of higher levels of fibrinfound in the DCS (discussed below). A comprehensive and quantitativeanalysis of histomorphometry and histopathology was assessed as part ofthis study, the specific results for mean injury score, mean intimalinflammation, mean percent diameter stenosis, mean fibrin score and %endothelialization for all three groups and are tabulated in table 11.As can be seen in table 11, the mean injury scores across the threegroups are very similar (no statistical difference), indicating thatthere were no significant differences between groups in regards to thelevel of mechanical vessel injury induced during stent implantation.Generally, an injury score of less than 1 is considered to be low.Similar to the injury scores, the mean intimal inflammation scores aresimilar across all groups (no statistical difference) indicating thatthe inflammation associated with both the coating alone (no drug) andthe DCS was the same as that of a stent with no coating at all. The mean% diameter stenosis data indicates no significant difference in cellularproliferation among groups with all groups showing low overall %diameter stenosis at the 28 day time point. This level of cellularproliferation amoung the various experimental groups is not unexpected,as the 1.10:1 overstretch results in relatively low injury during thestent implantation process. The mean fibrin score, which is used as anindicator for the biological drug response, clearly shows that the BMSand coating alone groups have similarly low fibrin scores, while thefibrin scores for the DCS group are significantly higher, indicatingthat the drug has been effectively delivered to the locally stentedvessel segment, demonstrating a clear biological response to theCompound D. This response is consistent with what has been observed withother commercial stent products containing Compound D or analogues witha similar mechanism of action. Lastly, the percent endothelializationindicates the degree to which the stent and stented vessel segment iscovered with an endothelial monolayer (an endothelial monolayer beingthe most intimal cell/tissue layer present in a normal functioningarterial vessel and is critical in preventing thrombosis). Theendothelialization data shows essentially 100% re-endothelialializationof the stented vessel segment across all three groups, indicating thatneither the base coating nor drug coating interfere with the endothelialhealing process.

TABLE 11 Mean Mean Intimal Mean Mean Implant Injury Inflammation % AreaFibrin % Group Score Score Stenosis Scores Endothelialization BMS 0.35 ±0.24 0.29 ± 0.42 18.94 ± 6.58 0.29 ± 0.21 99.67 ± 0.94 Coating 0.51 ±0.27 0.50 ± 0.53 23.39 ± 6.05 0.21 ± 0.31 100.00 ± 0.00  Alone (no Drug)DCS 0.47 ± 0.16 0.37 ± 0.99 22.07 ± 7.38 1.96 ± 0.75 99.92 ± 0.15

Numerous modifications and alternative embodiments of the presentinvention will be apparent to those skilled in the art in view of theforegoing description. Accordingly, this description is to be construedas illustrative only and is for the purpose of teaching those skilled inthe art the best mode for carrying out the present invention. Details ofthe structure may vary substantially without departing from the spiritof the invention, and exclusive use of all modifications that comewithin the scope of the appended claims is reserved. It is intended thatthe present invention be limited only to the extent required by theappended claims and the applicable rules of law.

All literature and similar material cited in this application,including, patents, patent applications, articles, books, treatises,dissertations and web pages, regardless of the format of such literatureand similar materials, are expressly incorporated by reference in theirentirety. In the event that one or more of the incorporated literatureand similar materials differs from or contradicts this application,including defined terms, term usage, described techniques, or the like,this application controls.

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described inany way.

While the present invention has been described in conjunction withvarious embodiments and examples, it is not intended that the presentteachings be limited to such embodiments or examples. On the contrary,the present invention encompasses various alternatives, modifications,and equivalents, as will be appreciated by those of skill in the art.

The claims should not be read as limited to the described order orelements unless stated to that effect. It should be understood thatvarious changes in form and detail may be made without departing fromthe scope of the appended claims. Therefore, all embodiments that comewithin the scope and spirit of the following claims and equivalentsthereto are claimed.

The invention claimed is:
 1. A solidified gel biomaterial comprising: athermally cured fatty acid based material having fatty acidscross-linked to other fatty acids via cross-linking bridges formed atunsaturated (C═C) sites of a fish oil from which the thermally curedfatty acid based material is derived; and a therapeutic agent loadedwithin the thermally cured fatty acid based material, wherein thetherapeutic agent is not stable when subjected to thermal curing thatthermally cures the fish oil; wherein the biomaterial is derived from apre-cure of the fish oil in combination with the therapeutic agent thatare, following combination, additionally thermally cured to form thebiomaterial, and wherein viscosity of the pre-cure is in the range of1×10⁵ cps at 22° C. to 1×10⁷ cps at 22° C. and the viscosity of thebiomaterial is greater than that of the pre-cure; and wherein thetherapeutic agent exhibits less degradation in the biomaterial thanobserved when cured with the fish oil by a thermal curing process thatstarts with uncured fish oil and ends with the thermally cured fattyacid based material.
 2. The biomaterial of claim 1, wherein thebiomaterial is hydrolysable by human tissue.
 3. The biomaterial of claim1, further comprising alpha-tocopherol disposed within the thermallycured fatty acid based material.
 4. A method of creating a curedbiomaterial comprising the solidified gel biomaterial according to claim1, the method comprising the steps of: curing a fish oil-containingstarting material for a first curing time to create a pre-cure materialby cross-linking fatty acids of the fish oil-containing startingmaterial; mixing a therapeutic agent with the pre-cure material tocreate a mixed preparation; then curing the mixed preparation for asecond curing time to create the cured biomaterial.
 5. The method ofclaim 4, wherein a higher percentage of the therapeutic agent remains inthe cured biomaterial after curing for the second curing time than wouldhave remained in the biomaterial if the therapeutic had been subjectedto curing conditions for both the first curing time and the secondcuring time.
 6. The method of claim 5, wherein the second curing time isshorter than the first curing time.
 7. The method of claim 6, whereinthe second curing time is at least twice as long as the first curingtime.
 8. The method of claim 4, wherein the viscosity of the pre-curematerial after curing for the first curing time has a viscosity of about1.0×10⁵ cps to 1.0×10⁷ cps as measured at 22° C.
 9. The method of claim4, further comprising mixing alpha-tocopherol with the fishoil-containing starting material or the pre-cure material.
 10. Themethod of claim 9, wherein the alpha-tocopherol is mixed with thetherapeutic agent and the pre-cure material to form the mixedpreparation.
 11. The biomaterial of claim 1, wherein the cross-linkingbridges include ester bridges.
 12. The biomaterial of claim 1, whereinthe cross-linking bridges include a combination of peroxide bridges,ether bridges and hydrocarbon bridges.
 13. A solidified gel biomaterialcomprising: a UV cured cured fatty acid based material having fattyacids cross-linked to other fatty acids via cross-linking bridges formedat unsaturated (C═C) sites of a fish oil from which the UV cured fattyacid based material is derived; and a therapeutic agent loaded withinthe UV cured fatty acid based material, wherein the therapeutic agent isnot stable when subjected to UV curing that UV cures the fish oil;wherein the biomaterial is derived from a pre-cure of the fish oil incombination with the therapeutic agent that are, following combination,additionally UV cured to form the biomaterial, and wherein viscosity ofthe pre-cure is in the range of 1×10⁵ cps at 22° C. to 1×10⁷ cps at 22°C. and the viscosity of the biomaterial is greater than that of thepre-cure; and wherein the therapeutic agent exhibits less degradation inthe biomaterial than observed when cured with the fish oil by a UVcuring process that starts with uncured fish oil and ends with the UVcured fatty acid based material.
 14. The biomaterial of claim 1, whereinthe cross-linking bridges include lactone bridges.